Since most of these cleanses are self-done, the only therapist that would be keeping a customer is yourself.
The reason to go slowly is that each cleanse releases toxins that need to be rehandled by your body on their way out. This is very hard work on the cellular level. The liver and kidneys are filters that need routine cleansing to declog. As you cleanse the bowels, etc., toxins are released in the blood stream. If done all at once or too fast, the filtering organs can be dangerously overloaded. This is NOT the way to good health.
There is no *instant* way to good health, good health is a way of life.