There are mistakes that seem to have a memory of their own. You correct a passage, manage to play it right a couple of times, and then, as if nothing had happened, the wrong note or the uneven rhythm creeps back in. This is one of the most vexing phenomena in the early stages of piano study, when the fingers seem to “get it” one day and “forget” the next. Most of the time, the issue is not with effort. It’s that the correction didn’t last long enough, or go deep enough, or move slowly enough to displace the old habit.
When a mistake recurs, stop calling the passage “the problem.” Pinpoint the exact source of the mistake. Maybe it’s the last note before the hand moves, or the first note after the thumb crosses under, or the entrance of the left hand after a long rest. Once you can locate the exact spot, play only the few notes leading up to the mistake, and not the full line or phrase. This forces the hand to confront the real problem, rather than hiding it within the context of a full attempt.
The mistake of correcting a wrong note by playing the full passage a few times, starting from the beginning, feels virtuous, but in the end it may mean practicing the mistake more than the correction. If the mistake happens three times, and the correction happens once, the fingers will still retain the weaker memory more strongly. Better to stop at the exact moment of the mistake, play the correct note or rhythm in isolation, and then play the corrected passage several times in a row. What matters here is not the emotional value of a given number of repetitions, but their accuracy. You’re not trying to prove that you can get through the passage once. You’re trying to make the correct version feel normal.
Sometimes a mistake recurs because the body is approaching it a different way each time. One time it uses one fingering, the next time it uses another, and then the hand falters, unsure of what to do. Fingerings, if necessary, should be written in, and then practiced consistently long enough to know whether they really work. The same goes for rhythm. If a bar feels uncertain, clap it, then count aloud, before returning to the keyboard. Many note errors are actually rhythmic errors in disguise. Once the rhythm feels clear, the notes will often follow.
A 15-minute practice drill for a resistant mistake might begin with a minute or two of very easy playing, to release physical tension and settle the finger action. Spend about five minutes practicing the exact trouble spot, hands alone if need be, at a tempo that allows you to think. Then connect the corrected passage to the surrounding musical phrase, so it doesn’t feel disconnected from the music around it. In the final minutes, play the full phrase a few times, but don’t go so long that you tire and turn careful practice into sloppy guessing. It’s always better to end with several successful attempts than to persevere until you start to get fuzzy.
If a mistake still resists, try a different kind of drill rather than repeating the same failed attempt. Play the passage with a brief hold before the tricky note. Then play it with a brief hold after the tricky note. Play it very softly, so you can hear the physical effort. Play it with one hand while silently tapping the rhythm of the other hand. Such shifts in approach can clarify exactly what the hand or the ear still doesn’t understand. Often, a resistant mistake isn’t resistant at all. It simply hasn’t been approached from the right angle yet.
Progress at the piano is seldom linear. A recurring mistake can be demoralizing, but it can also point to the very technical skill that needs the most attention right now. When you learn to regard the mistake not as a failing, but as information, practice will become less frustrating, and more productive. A passage that seemed undoable last week can become solid next week, once the correction is precise enough to stick.