Often, CFI's who charge appropriately for their time are thought to be overcharging their students. In my opinion, all CFI's should charge for the following times, not just hobbs time: preflight briefing, the walk out the the airplane, preflight inspection (if not already completed by student), hobbs time, time to walk to building from airplane after lesson, and debriefing time.

Most students really do not value the time of their instructor and only wish to pay him or her for the hobbs time.