I've secretly taught 4 friends who to roll in a kayak. I feel like I have to apologize to the first person I've ever tried teaching because he was like a guinea pig to me. It took him quite some time before he successfully managed to roll. Don't think I helped much.
But when I can get Huan Da the jelly belly up and rolling, I know for sure Im getting somewhere. Earlier on, I had a more rigid approach, teaching only the C to C roll. But recently, I showed both the Sweep and C to C letting whoever was trying to learn to have a feel of both.
Although Huan Da's roll isn't perfect, its a start. He has at least a 70% chance of successfully completing the roll. Not bombproof, but an important step nonetheless. This allows him to concentrate more on improving technique rather than trying to get out of the water.
I also taught a "technique" where he floats himself to the surface after a failed rolling attempt to get a breath before attempting to roll again.
Regarding the issue on fiberglass kayaks on sand, I've spoken to a few people and it just seems that some coaches have very rigid mindsets. Since most coaches learn by emulating, it is only natural for them to emulate their instructors or mentors. I guess its a matter of whether they question the methods and filter out the useless stuff.
I am still new to coaching, so I will stick around Water-Venture for a little longer. Gaining experience till the time I feel that Im stagnating.