Sound advice, I think. Keep trying, push the envelope, or what will become of your life? What?
I tell this to every pupil, group or choir i work with.
And i defy any honest musician to say otherwise.
the ART in the performance is in making the mistake, following it with the most beautiful passage, and with such confidence that should make the listener wonder if they hear you make a mistake at all.
so teachers, TEACH your pupils how they must expect a mistake to happen, and they need not go back and correct it, but need to RECOVER professionally WHEN you play a wrong note. AFTERWARDS you practice that part which tripped you up and it should not be the same mistake tomorrow!