The 'patient' in this case is a learning tool. It's not a regular cleaning appointment. You get nearly free dental procedures, they get you in chair for 15 to 20 hours over the course of a couple months. That's the trade. That's why you have never experienced anything like this before. If you have dental insurance then this really isn't "worth it", unless you want to help dental assistants. If you have no insurance, then this is a great deal, provided you have the time.

Just like if you can afford to rent a jet ski, sitting in a 2 hr time share pitch for a jet ski rental isn't worth it.