It is possible to hack away at a trouble spot for several minutes, constantly repeating it and beating it into submission, and then be able to manage it, more or less. I am sure a statistician would be able to come up with the odds for this being so. Apart from being incredibly unskillful, it is a waste of time because the following day you will most likely be back to square one. Practising like this is like building your house on sand – some days all will be well, but on others, the whole thing just collapses.

In performance we can’t take multiple stabs at something, it has to be right first time and this fact needs to be reflected in our practice. Think about it – if we never practised errors, we’d probably never play any!

I would have to go further – it has not only to be right but also to feel easy.

There is no such thing as a Difficult Piece.  A piece is either impossible – or it is easy. The process whereby it migrates from one category to the other is known as practicing.  (Louis Kentner)

Trouble spots are like bad apples or unruly kids in a class. Left unattended, they ruin the good ones. Identify the trouble spots in the piece, those places that trip you up and cause you to stumble and fall (and affect subsequent parts of the piece you know perfectly well) and isolate them. They will usually consist of small parts, perhaps a bar, or even a couple of notes that derail you (but may of course be longer).
Put them in the equivalent of pianistic detention for a few days and give them special attention. For my younger students, I mark these in the score with square brackets and next lesson I will hear these extracts first. If they are still not right, I will work on them with the student but will make a point of not hearing the piece as a whole until these passages have been mastered (thereby training them how to practise).

TOP TEN WAYS TO PRACTISE TROUBLE SPOTS

10. Practise the spot ultra-slowly, also with separate hands.

9. Starting from the beginning of the spot, add a note (or a beat) and repeat this. Go back to the beginning of the spot and add another note (or beat) and repeat this. Etc!

8. Start from the end of the spot by playing the last note (or beat). Now add the note (or beat) before this, and repeat. Follow this process until you reach the beginning of the spot.

7. Start anywhere in the spot. If it is a longer section, begin from any bar. If it is a small section, begin on any beat, or any note.

6. To reincorporate a former trouble spot back into its surroundings, you can add the bar before (or whatever smallish section makes sense), and now begin from there.

5. Next, do this with the bar or section that comes after.

4. Finally, play the bar before, the bar itself and the bar after. Don’t forget to STOP at the end of your predetermined section, to evaluate (see 3.) and then repeat it. The tendency is to carry straight on – resist this though.

3. Use a feedback loop between each repetition so that you can identify precisely where the problem lies and mentally rehearse it before repeating it. You’ll be repeating with a definite purpose, and the feeling of starting each repetition from a clean slate.

2. Transpose (very slowly). Perhaps not for youngsters, but don’t put any limitations on them either!

1. Return to the trouble spot frequently throughout the practice session. Go back to it between pieces, so that you approach it from fresh each time. Also, make a special trip to the piano outside of your regular practice routine, just to play this one extract. This might take just a minute or two!