How many sessions of hypnotherapy are required

This depends on 2 variables, how responsive the client is to hypnosis, and the complexity of the issue being dealt with.  For a client of average responsiveness most individual issues can be dealt with in 3-6 sessions. Some quicker for example smoking or simple phobias often only require 1 or 2 sessions. More complex issues can take significantly longer, for example for OCD and eating disorders.