Have you been at any deliverance meeting and observed how it is sometimes challenging to cast out certain devils? After a period of time we hear the common phrase; “send him/her to the back”. That is where the prayer warriors deal with the devil.
If we want Jesus results, we ought to do things the Jesus way. Jesus never spoke to a demon, sickness or any situation more than once.
Let’s take a look at this story closely
Mark 9:25-27 KJV
 When Jesus saw that the people came running together, he rebuked the foul spirit, saying unto him, Thou dumb and deaf spirit, I charge thee, come out of him, and enter no more into him.
 And the spirit cried, and rent him sore, and came out of him: and he was as one dead; insomuch that many said, He is dead.
 But Jesus took him by the hand, and lifted him up; and he arose.
After Jesus had spoken to the deaf and dumb spirit, did it leave instantly? The scripture above says the spirit now tore the boy even more. (We would have said the demon is manifesting). Did Jesus call for backup? No he didn’t.
Before Jesus came to the scene, the disciples were casting and casting to no avail because of the lack of faith. When they speak to the demon, it tears the boy the more so they speak again. They increase the volume of their voice and add other gymnastics: all these being a demonstration of the lack of faith
Brothers, if you speak to any sickness, demon or situation, it changes. The devil just loves to play tricks with your mind and when you fall for it, then he knows you do not have faith. Every time the word of God goes forth, the devil will sure shake himself a bit by creating a contrary situation. Don’t fall for it.