Good article as a whole, but I object to this:
"Mistakes cost far too much time to repair and only create uncertainty, whereas your practice ought to build security. Remember, your performance is a direct result of how you practice, and efficient piano practice means playing correctly. If you start making mistakes, it means either that youâ€™re going too fast to learn the music or that your brain is tired. If thatâ€™s the case, itâ€™s best to take a break and do something â€“ anything â€“ else."
Well, you HAVE to make mistakes. If you never make them, it basically means you are not making any progress, that you are only maintaining what you already master. Of course this maintenance work is also absolutely necessary, but when you try to develop as a pianist it is necessary to stretch your boundaries - get to the point where you make mistakes, that is, to see where you need to work more. I can assure that every ice skater EVER who can do a perfect triple Lutz has failed, stumbled and fallen a zillion times. They know that falling is a part of the learning process. A pianist also has to "fall" and it is easier for us, thank God, as we don't risk breaking a leg while we do it.
On the other hand, it is also, of course, correct that you should not just make a bunch of mistakes and ignore them, in the vague hope that they will be gone by themselves next time you play this section ... It is also correct that you shouldn't ignore the signals from you brain and body that enough is enough, that you need a break. But I get a bit worried when I read "never make mistakes" because that will lead to a very tense attitude towards mistakes. You WILL make them, and "not allowing yourself" to make them is like giving yourself a mental whiplash whenever it happens - oops, what must not happen just happened! D***! I have been there and I can tell you this road does not lead to happiness. So, let the mistakes happen, be happy for them, work with them until you have thoroughly identified WHY they happened, and then work out a solution.
Repetitions, how many? Depends on the length of the section, I would say. If you cannot nail a certain combination after, let's say, six or seven repetitions, you have too much to handle. Narrow it down.