Its a good question.

My experience suggests that climbers up to the 5.12 level are making al kinds of mistakes. The definition of a 5.10 climber seems to be someone who makes basic sequencing errors on just about every move.

By the time a climber gets to the V10 / 5.13+ level they have usually had a lot of bad habits beaten out of them but they can still have a lot to learn. Thinking about my experience with climbers at that level I would say they are still learning and refining movement just like everyone else, but they can do it faster. I've spend the most time helping them learn to gain control over their movement initiation, timing, and pacing. The other thing is that what limits them on a given move or climb is often not things like obvious sequencing errors. Its often things that lie below their perceptual threshold. They know that the move isn't working but its actually impossible for them to perceive why because they are doing just about everything right and the problem occurs very quickly, say 1/30 of a second.