There is nothing on the grade exams or TCRG test that proves if you will be a "good teacher". You have to be able to dance and memorize lots of stuff to pass the tests. You actually don't even need to dance "that well" to pass the grade exams (which is fine).
There is a lot more to running a business and teaching people effectively then being able to dance steps and regurgitate archaic figure dance linguistics.
The grade exams are a money grab (in the context of requiring them for the TCRG exam). I honestly think the Grade Exams are a great/fun/encouraging thing for dancers to do as they move through the levels. We would have loved doing them, when we were dancing, but they weren't offered where we lived, and we had never HEARD of them until my dancers was in her 20's, and suddenly they were a requirement for the TCRG exam.
Having to spend all the money and time going through them, starting when you are in mid 20's and qualifying for Worlds, in my opinion, is a pointless money grab.
If CLRG wants more dancers, then revamp the certification process and make it realistic to what you are doing, teaching Dance. This is not brain surgery.
We can't even find out when/if/how often they are offering the TCRG exam. It's like cracking a International spy code for pete's sake. Get real.