How many HBOT sessions will I need?

It depends entirely on the condition. Chronic diabetic wounds and radiation injury typically involve a course of 20–40 daily sessions. Some acute or emergency indications need only a handful. Your treating physician sets the plan based on the diagnosis and how you respond, and it's re-evaluated as you progress. Anyone quoting a fixed number before assessing you — or selling large prepaid packages up front — is a flag worth questioning.