I’ve recently found out that my sweet spot to determine when to move to the next item when learning fast lines from a book or video instructional is if I can play a phrase at any equivalent of 16th notes at 140-150 bpm, and I feel that, from that point, my brain simply takes care of everything on its own and I am usually able to play at higher speeds once I stop trying so hard. I guess that’s the 85% they talk about:
Do you have any specific criteria to decide when to move forward in your learning journey? Do you stick to the one thing until it sounds “like the recording”?