These methods will work if done in the name of Jesus, however when they are carried to extremes the enemy wastes a lot of time and energy. These methods are usually not necessary, but God honors them many times because the practitioners are unsure of the proper procedures, and perhaps this is the only teaching to which they have been exposed. God sees their hearts and He knows they are trying to help people get free, so He delivers them in spite of the techniques. The Biblical method for casting out demons would be to pray as the Holy Spirit directs. The most important thing is to listen to the Holy Spirit's direction regarding individual cases.
Faith is the key to getting people free of demons.
We must have faith when we pray that the demons will leave. Or we can even lose the battle if we don't stand firm in our faith and trust in Jesus. Some deliverance does require a prayer battle as little or no intercession as been previously done for the person bound. Jesus' disciples had a problem with not being able to cast out a demon from a child because they lacked faith. And he said unto them, This kind can come forth by nothing, but by prayer and fasting.