"If you can't draw something, it just means you don't fully understand it yet."

I'm paraphrasing but that's a cool little saying I like. Once I understood skirts "squished" at the top by pulling a line, I immediately understood why it folds like that and I immediately got better at drawing them.

But that is not always the case. Some stuff that is very organic and require precision (like human anatomy) can't be simply understood. I doesn't matter how many tutorials on hands I watch, or how many little tricks and patterns I try to come up with, there is too much to grasp and references end up being the only way to get a believable result.

For people who have achieved good anatomy, would you say you have "solved" some puzzles that allowed you to improve? Are there eureka moments, and are they a big part of drawing well, or does forced memorization/measuring work better in this case?