My son learned deliberate practice young (10?). He'd play through a cello piece phrase by phrase, carefully, slowly then speeding up, getting it exactly right b

My son learned deliberate practice young (10?). He'd play through a cello piece phrase by phrase, carefully, slowly then speeding up, getting it exactly right before moving on to the next. When he'd finished a piece to the end, he could discard the sheet music and just play it. Because it was now a familiar map in his mind. The trouble with just running-through a piece without doing it deliberately is, now you've poisoned yourself with a shoddy performance. You then have to unlearn your initial mistakes.