When you are having CBT treatment, you usually have regular weekly sessions with your therapist. A session typically lasts for around an hour.
Your CBT therapist usually uses the first one or two sessions to make an assessment of your condition, and to formulate a treatment plan. This assessment is different from any assessment that another therapist might have made in the past, so it is always needed.
The treatment plan will include an estimate of the number of treatment sessions required. Between four and ten treatment sessions is typical.
Some patients improve unexpectedly quickly, and need fewer sessions than was estimated. Some patients improve more slowly than expected, and might be offered additional sessions.
After your treatment is complete, you might be offered some follow-up sessions at longer intervals, perhaps a few months, to ensure that the improvement has been sustained.
So CBT treatment usually takes at least several months, but it is rare for it to last more than a year.
The benefits of CBT can be ongoing, however, because during your treatment you acquire tools and skills that you can use throughout the rest of your life without involving any therapist.