How often on average can one person get episodes of depression how long does it last?

No simple answer: Each episode of depression, especially if not treated to remission, increases the chance of getting another. Through therapy, one can get coping skills that can diminish the chances of getting another episode by being better able to deal with stress. Genetics plays a role as well as life circumstances. After 3 episodes, the apa recommends maintenance treatment.

Depression: I'm not sure there really is an average, per se. The most responsible answer I can give you is that it depends on the patient, and depression means different things to different people.

Individual: It varies widely. Some people may have just one episode and recover. Others have a life long affliction that may not respond to treatment. Exercise, psychotherapy and medications do help. Wish you good health!