The way that they measure success is often via the quack-chiropractor "resist when I push here" method, and they often even suggest to you what you're supposed to answer.
It strikes me that it could be so much better.
We could easily have 3d cameras pointed at you while you do certain moves that record the way you move. We could have tape-on electrodes that track your muscle firing.
I believe strongly in immediate feedback while doing moves; you want a realtime analysis system that shows you on a screen how your muscles are moving. It's so much easier to correct your body and do things right if you can see it.
(this is even ignoring the issue that a huge percentage of PT's are either grossly incompetent, negligent, or just quacks)