I try to not get too uptight with that. Before a run, I take a mental note of how things look and how I assess my position/movement relative to ideal, and then see how the run turns out. If it's off or otherwise whacky and I notice that multiple times, I have a pattern that I can correct. Simplified example: Rolling too late -> exessive dive. So if I notice that I keep diving exessively, I know (assume) that I roll too late.
For similar parameters, I set myself up with a small range (WPs placed in a square) so that I always fly in the same area. My range pattern is far from perfect, but works better than the things I tried before.