Have you ever personally had a Miracle? I have had dozens and dozens, from tooth aches, headaches, aches and pains, witchcraft attacks, and cysts disappearing immediately after praying. I also have had dozens and dozens of headaches that did not go away. No one knows why, but we don't always get healed when we pray. Sometimes we do and sometimes we don't. That really is God's business.
Well, DELIVERANCE is the same way. Most of the demons do in fact leave when you command them to leave in the name of JESUS. He did tell us to do that, remember. However, there are times when we cannot get rid of IT. No one can tell you why either. Demons work on legal grounds most of the time. It's like they have a "lease" to be in you. If you were in the occult at one time, this would be legal grounds. You can command them to leave all day, but they don't have to until the occult is renounced by the person. This "renouncement" breaks the lease.

Most demons come out immediately. None of them want to leave their "house", and sometime put up quite a fight. Plan on spending more than a few minutes on THESE KIND. We spent four hours one time on ONE demon before IT left. Sometimes the demons will not leave until you find out what their legal grounds are. It takes persistent Spiritual Warfare to cast OUT some demons. Also, the demons know if YOU really know the power you have in the name of JESUS. You can't fake out a demon, and especially don't want to mess with them if there is any fear in you. Fear is a demon, by the way.
I was watching the landscaping people at these new apartments. They brought in pallets of grass sod. Then they would pick up a piece at a time and lay it on the bare ground. It would lift right off the stack of grass.
Well, some of the pallets of grass sod sat there for a few weeks without being used. It sat through the sun and the rain, just the right things to help it grow.
When they came back to pull off the top piece of sod, it was difficult to lift it, because the roots started to go INTO the sod piece below it. It took some pulling, but they were able to lift each piece off.
There were several other pallets, however, that they were not able to use because the demon roots, I mean grass roots, grew through each piece of sod so much, that it was like ONE piece of sod stacked up. The whole pallet had to be cut up and destroyed.
Demons work just like the grass sod. When they enter INTO you, they look for a good spot that is not already taken, and then they let their roots start hooking on to everything it can. The longer the demon has been IN you, the further his root system is IN you.
If you have ever tried to pull up grass by the roots, it is a tough job. Sometimes you think you got all he roots, but it grows back. What do you do? You pull some more!
When you have cast OUT a demon in the name of Jesus, and you still have your problem (demon), do some more DELIVERANCE. Be persistent. Hate the demon. Grit your teeth if you have to and say