While listening to Manuel Barrueco’s podcast, he was asked about whether slow practice was a good method. Here was his response:
“[Slow practice] is a very good method, perhaps it’s the best, I’m not sure if it’s the best, but it’s one of. I think slow practice is extremely helpful in a lot of ways. It helps with memory because it breaks down muscle memory. It also allows one to look at the technique very closely. And look at any excess motion, bad movements, and tension in the technique. Also, it gives the hand and the fingers time to learn how to do their job. Also, their is another aspect that is often underrated which is that it is good musically. By practicing slowly, it allows you to slowly hear the harmonies and the lines and everything that is going on in a piece of music. So I wouldn’t be surprised if it is the best technique to practice in.”
With that in mind, try practicing a piece like the Allegro from Agustín Barrios’ La catedral at 60bpm per sixteenth note.