It sounds like a lot of men end up needing more than one hair transplant. Is this always the case or are there ever times when a single session is sufficient?
This depends strictly on the nature of hair loss, both in terms of its progression and in its area. Some men progress only to a certain specific, sometimes only small, amount of hair loss and in that case a single hair transplant may suffice. There are other men whose hair loss progresses to almost the entire scalp, in which case more than one hair transplant is usually recommended if the patient desires to have extensive coverage. It all depends too on the age that the transplant is done. If you are young and continue to lose your hair, you may need a second or third transplant to keep up with the progression of hair loss.