Hypnosis is the art of inducing different trance states, not the induction of one state. Hypnosis is just the term given to the advanced communication skills used for doing this.
Classic “hypnotic” trance state is where a person has been guided into a “peak learning state” where they are able to learn new information (updating old patterns) or learn greater control over themselves (like over unconscious processes etc.). Hypnotic techniques can also be used to induce relaxation, anger, confusion, fear, pain, love, sadness, desire, or any other trance state.
On average in an hour session a therapist will probably spend about 15-20 minutes gathering information/history about the problem, the process, how the problem starts and ends, a few examples (so that the therapist can hear the client describing the problem), the context, whether they have solved the problem in the past (For example; perhaps they want to quit smoking and they did for 5 years 10 years ago, then the therapist can find out what is stopping them doing the same again and what made them restart), etc… but with some people they have a need to talk for longer and feel listened to and other people give what you probably need really quickly (Many phobia clients can be helped in less than 10 minutes)
