Advice on Getting Better from an Accomplished Piano Player (2011)
Some of this advice echoes that in Fundamentals of Piano Practice by Chaun C. Chang.https://fundamentals-of-piano-practice.readthedocs.io/en/lat...Chang precisely recommends the same thing: don't just practice by going through pieces from beginning to end repeatedly. Being a scientist, he quantifies that with efficiency arguments, which are along these lines: if a five minute piece contains two-bar difficult passage, then you can only practice that passage twelve times in the span of one hour.  If the passage is only ten seconds long, you can practice it twelve times in just two minutes, which is 30 times more efficient.One tools is to use a metronome to find the stress passages in a piece. Without a metronome, we hide the stressful passages by slowing down subconsciously.Set the metronome at a baseline rate at which you can play everything. Then gradually crank up the speed. Then the stress points show up: passages where you fumble.Chang makes astonishingly clever observations about speed.  Basically, speed has two extremes that are easy: very slow, or super fast.   It's just as hard to slow down from high speed playing as it is to speed up slow playing.  The initial argument he makes is that there is no faster way to play three notes than to just hit a three note chord with three fingers, which is easy, and "infinitely fast".  Moreover, it is basically easy to slow down from that "infinite speed" a little bit; if we hit the chord so that the fingers are staggered slightly, we will play a fast arpeggio.   A really fast run of notes is like that: hitting groups of notes in this manner, and changing the hand position in between those groups.