I cant speak for CASI, but for AASI, it is not really about tasks. What it is about is the rider`s fundamental body movements and the consistency of those movements. In an AASI exam, you can actually eat shit doing a task and not fail so long as the specific body movements that the examiners are looking for are present. I would`nt exactly want to eat shit on every task and expect to pass though. But, the point is it is really more about very specific movements.
A really good rider that can out ride an examiner, can easily "fail" an exam if they are not using the specific movements AASI is looking for. This is why there is some real contention in snowboarding with AASI. Many really good riders feel they are too narrow in their vision of what "correct" movements are. The issue to keep in mind is these movements they are focusing on is for the teaching environment. I can pretty much bet, these same examiners ride for fun with a lot of their own personal flair and style and the AASI manual is left on their desk.
i liked that last bit. thats a good point. Im going to take a wild shot and say that my own riding style is not right along with the guide lines of the instructor's book. i guess its about knowing how to change to go from perfect form to your own spin on the form. i think it would be fun to take the class and the course and see where i fall. after teaching a few people i think i have the basics of explaining and teaching the movements.