Copied from Chick Corea’s question page at www.chickcorea.com.:
Q: I would like to know more about how you manage practice time—specifically, how you know when it’s time to stop practicing something and move on. Also, how do you make the mental switch from practice to playing? — Sam D.
A: Thanks for your question—it’s a good question. To learn how to prepare properly or practice properly, to make advances in one’s technique, or knowledge at the instrument, or music in general, is a really important thing.
The main thing that I can see about practicing—and it’s also true about playing—is that the very basis of practicing, and knowing “when” and “how” and all of that, stems from first having an intention to advance, an intention to improve. An intention to take a certain challenge, or a certain piece of music or a certain phrase, or any particular thing that you think of, and then you have an idea that you would like to improve it, and you also have an idea of how it probably would sound, when it sounded right.
And this is another real important aspect—how you know when you’ve arrived, is that you have to trust your own judgment of what it should sound like. You can’t just accept another’s opinion about it. If a teacher is listening to you practice, and they say, “Oh yeah, that’s right,” when you play, you have to make sure you understand that that’s someone else’s opinion; it’s not yours, unless you can also see that same thing.
So it’s all about one’s own understanding of what his own goal, or target, or object of accomplishment, is. You have that in mind, and then you just go for that. You apply yourself calmly, and create the time, and you just keep doing it, until you’ve got it.
That’s the simple explanation of how to practice. I try to do that, and I get better at it, actually, as I get older. I learn more and more how to do that. And how to slow things down, sometimes, to the right speed, in order to understand every little part of it. You don’t want to go too fast or too slow, but just at a tempo and pace that you can have success at, and really know that you’re gaining on your goal.