The Catholic Church cannot really cast out demons.  You are not told about exorcisms that get no results.  The ones you are told about are few and far between for confidentiality is a serious matter.  I remind you of a gospel story where Jesus encountered a man who went to Jesus' disciples to get a demon cast out of his son.  They couldn't do it.  Jesus berated the man for his lack of faith and about "you unbelieving generation, how long shall I have to endure you?"  The man brings his boy to Jesus and we are told the demon responds by tormenting the boy.  Jesus drags it out to make a point. They chat and then he decides to instantly eject the demon.  The message is clear, if you take your child to the Catholic Church you are not a believer.  Another message in the story is that Jesus stood there while the demon threw the boy about presumably trying to injure him terribly.
Exorcisms are based on a religious culture and systemic superstition where there is a clear and disgusting gender bias.  Most stories are about possessed women or girls.  The ratio looks like more than 70% female.  Jesus is on record as casting out the demon of a pagan girl at a distance like he could not bear to help her.  As for boys he dealt with them face to face.
The story of Anna Ecklund's exorcism is revolting and one of the more extreme accounts that would please a film maker. Most accounts are banal and dull. This makes you wonder if what happened to her is based around lies.

An American woman - real name Emma Schmidt was possessed and exorcised over decades. The woman was given the false name of Anna Ecklund. 

The final exorcism lasted from 18 August to December 23 1928 in Iowa and brought her to a remarkable level of physical dissipation. She had not been eating during that time. A tobacco type material was often vomited up. Her lips allegedly turned the size of her hands. The "demons" present included Judas Iscariot and her father and evil aunt Mina.

This case provides evidence for the following.

The sacraments and her devotion did not stop her getting possessed.

That evil spells and curses work.

The Devil is able to stop God giving you the grace to pray. The faith says prayer is a gift from God.

That a dead person can become a demon or a cause of evil in your life. The account names Mina and Judas Iscariot as being worse than the actual demons.

That though a demon brings hell with him wherever he goes he is still better off and not suffering as much if he roams the earth.

That the devil is cruelly treated during the exorcism. The account mentions "the tortures of exorcism".
That the demons are accused of being just evil and not insane or just warped.  That is judgemental hate for where is the innocent until proven guilty?

That a complete exorcism may not happen. Afterwards the possessions were described as mild and manageable. So she had relapses after the demon was got out. It obviously still had a foot in the door.

Concerns:

There is no proof that when she screamed in agony that it really was the devil and not her. What if it were both? Satan would let her personality be present enough to suffer with him.

The account says demons were able to do the miracle of getting her to levitate and make her lips swell to the size of her hands so they can clearly do stigmata or fake resurrection visions or move stones from tomb entrances.

The idea of trying to send entities back to Hell does not fit the modern notion that God sends nobody to Hell but you go there yourself.

The lessons are that God seems very inept ... or the Catholic Church cannot really get demons out.

That there are silent demons who are so stupid that they cannot do evil properly meaning they could be infesting everybody. When they are ejected a new swarm takes their place.

It is an advert for cursing people and black magic.

It implies a Satan who may like God limit what he can do but one who is essentially just God's equal.

The case looks like trying to fight black magic with more black magic or to replace a curse with a lesser curse and call that a good result! If anything it makes you think of how tradition accused Jesus of dabbling in dark forces and using them.

"Experience teaches us that at times they pretend to leave the possessed entirely at ease for a while, in order to sidetrack the unwary observer and thus outwit him."

Begone Satan! by Reverend Celestine Kapsner 1935 purports to tell us the story. Let us look at the most important parts.

"The unfortunate woman was unknown to the pastor. She lived far from Earling, and up to then he had heard nothing about her. The Capuchin Father had explained to him what her actual condition was, that she was a very pious and respectable person. Throughout her youth she led a religious, fervent and blameless life. In fact she approached the sacraments frequently. After her fourteenth year some unusual experiences manifested themselves. She wanted to pray, wanted to go to church and as usual receive Holy Communion. But some interior hidden power was interfering with her plans. The situation became worse instead of improving. Words cannot express what she had to suffer. She was actually barred from the consolations of the Church, torn away from them by force. She could not help herself in any way and seemed to be in the clutches of some mysterious power."
....

"Hallucination, a pure hysterical case, nervous spells." Such easy explanation one will hear to account for the experiences. True, similar happenings do occur in nervous and hysterical cases. However, many doctors had this case in charge for years, and the woman was finally examined by the best specialists in the profession. But their thorough examinations resulted in the unanimous conclusion that the woman in question did not betray the least sign of nervousness, that she was normal in the fullest sense. There was not the slightest indication suggesting physical illness. Her undeniable and unusual experiences could not be accounted for. As the doctors could not help her, it was thought to see results in another field.

Many years passed. Finally, recourse was had to the Church and the supernatural powers of the priesthood. But a reserved and skeptical attitude was maintained for some years towards proceeding with exorcism. Examinations and observations were constantly made. It gradually became evident that strange preternatural powers were at play. The woman understood languages which she had never heard nor read. When the priest spoke the language of the Church and blessed her in the Latin tongue, she sensed and understood it at once, and at the same time foamed at the mouth and became enraged about it. When he continued in classical Latin, she regained her former ease. She was conscious at once when some one gave her articles sprinkled with holy water or presented her with things secretly blessed, whereas ordinary secular objects would leave her perfectly indifferent.

....

The two priests arrived without the slightest trouble Thank God, the woman also had arrived safely at the Sisters' convent. With this reassurance the difficult task could begin quietly on the morrow. However, that very night the enemy displayed his true colors. News was soon dispatched from the convent to the rectory next door that the woman caused difficulties from the very start. The well-meaning Sister in the kitchen had sprinkled holy water over the food on the tray before she carried the supper to the woman. The devil, however, would not be tricked. The possessed woman was aware at once of the presence of the blessed food and became terribly enraged about it. She purred like a cat, and it was absolutely impossible to make her eat. The blessed food was taken back to the kitchen to be exchanged for unblessed food; otherwise the soup bowls and the plates might have been crashed through the window. It was not possible to trick her with any blessed or consecrated article; the very presence of it would bring about such intense sufferings in her as though her very body were encased in glowing coal.

....

Father Theophilus had hardly begun the formula of exorcism in the name of the Blessed Trinity, in the name of the Father, the Son, and the Holy Ghost, in the name of the Crucified Savior, when a hair-raising scene occurred. With lightning speed the possessed dislodged herself from her bed and from the hands of her guards; and her body, carried through the air, landed high above the door of the room and clung to the wall with a tenacious grip. All present were struck with a trembling fear. Father Theophilus alone kept his peace.

"Pull her down. She must be brought back to her place upon the bed!"

Real force had to be applied to her feet to bring her down from her high position on the wall. The mystery was that she could cling to the wall at all! It was through the powers of the evil spirit, who had taken possession of her body.

Again she was resting upon the mattress. To avoid another such feat, precautions were taken and she was held down tightly by stronger hands.
....

"But you will obey! The power of Christ and the Blessed Trinity will force you back into the pit of hell where you belong!"

Then followed a load roar and protest: "No, no, only spare me that!"

As the prayers of exorcism were continued, Jacob's mistress, who was in hell with him, also had to face the ordeal and give answer. Her high pitched voice, almost a falsetto, had already been noticed among the many other voices. She now confessed that she was Mina.

Mina admitted that the cause of her damnation was her prolonged immoral life with Jacob while his wife was still living. But a more specific cause for her eternal woes in hell was her unrepented acts of child murder.

Exorcist: "You committed murder while you were still alive? Whom did you kill?"

Mina, bitterly: "Little ones." Evidently she meant her own children.

Exorcist: "How many did you actually kill?"

Mina, most unwillingly, curtly: "Three--no, actually four!"

Mina showed herself especially hateful. Her replies were filled with such bitter hatred and spite that they far surpassed all that had happened so far. Her demeanor towards the Blessed Sacrament is beyond description. She would spit and vomit in a most hideous manner so that both Father Theophilus and the pastor had to use handkerchiefs constantly to wipe off the spittle from habit and cassock. Because of her unworthy communions, it was clear that the Blessed Sacrament, the Bread of Eternal Life, which should have been the source of her eternal salvation, turned out to be unto her eternal damnation. For she tried to get at the Blessed Sacrament with a burning vengeance and hatred. Out of this group of devils, Mina and Judas were the worst offenders against the Blessed Sacrament.

As the days passed by, a rather odd change manifested itself in the disposition of the pastor who began to experience a rather strong antipathy against the whole procedure of driving out of the devil.

...

The number of silent devils was countless. Apparently they were from the lower classes, for they displayed no marks of strength or power. Their voices were rather a confusion of sounds from which no definite answers could be distinguished. There was no articulate speech, rather a pitiful moaning and subdued howling. They could put up little resistance against the powerful effects of exorcism. It seemed as though they came and left in hordes, one crowd being relieved by others of the same type. They reminded one of a traveller who is suddenly overtaken by a swarm of mosquitoes. A few puffs of tobacco drive them away, but in short order they return and pester him again.

...

At one time the evil spirits howled and yelped fearfully when the prayers of exorcism were solemnly pronounced and when the blessings with the relic of the cross and the consecrated Host were given: "Oh, we cannot bear it any longer. We suffer intensely. Do stop it, do stop it! This is many times worse than hell!" These groans, indicating the attendant pain and suffering, cut to the quick.

"Therefore, depart at once, ye cursed! It is entirely within your power to free yourself from these sufferings. Let this poor woman in peace! I conjure you in the name of the Almighty God, in the name of the Crucified Jesus of Nazareth, in the name of His purest Mother, the Virgin Mary, in the name of the Archangel Michael!"

"Oh, yes," they groaned, "we are willing. But Lucifer does not let us."

"Tell the truth. Is Lucifer alone the cause of it?"

"No, he alone could not be. God's justice does not permit it as yet, because sufficient atonement has not yet been made for her."

This admission was valuable. It offered a greater inducement to arouse the members of the parish to increase their acts of expiation for the woman.

... They knew that victory was not far off. During the latter days the devils betrayed great fear lest they be forced to return to hell. ....They pleaded pitifully: "Anything but that, anything but that." To be banished to another place, or into another creature would have been more bearable. They did not want to be driven back to hell.

"But you are already in hell."

"True, true," they groaned, "we drag hell along with us. Yet it is a relief to be permitted to roam about the earth until (at the last judgment) we shall be cast off and damned to hell for eternity."

...

Gradually the resistance of the devils began to wane. They seemed to become more docile. Their bold, bitter demeanor gave way to more moaning and despairing tones. They could not bear the tortures of exorcism any longer. With great uneasiness they explained that they would finally return to hell. But how often they are deceptive and unreliable! Experience teaches us that at times they pretend to leave the possessed entirely at ease for a while, in order to sidetrack the unwary observer and thus outwit him. For this reason Father Th., almost completely exhausted, demanded in the name of the Most Blessed Trinity that at their departure the devils should give a sign by giving their respective names.

"Yes," they promised emphatically.

It was on the twenty-third day of December, 1928, in the evening about nine o'clock that, with a sudden jerk of lightning speed the possessed woman broke from the grip of her protectors and stood erect before them. Only her heels were touching the bed. At first sight it appeared as if she were to be hurled up to the ceiling. "Pull her down ! Pull her down" called the pastor while Father Th. blessed her with the relic of the Cross, saying: "Depart, ye fiends of hell! Begone, Satan, the Lion of Juda reigns!"

At that very moment the stiffness of the woman's body gave way and she fell upon the bed. Then a piercing sound filled the room causing all to tremble vehemently. Voices saying, "Beelzebub, Judas, Jacob, Mina," could be heard. And this was repeated over and over until they faded far away into the distance.

Vogel, Rev. Carl. Begone, Satan! A Soul-Stirring Account of Diabolical Possession in Iowa. Rockford, Ill.: TAN Books and Publishers, 1973.