Some are quite fastidious and are very driven to the fixing of these minor annoyances and those are the people who end up becoming very pianistic, or well-rounded piano students.
But you have to weigh up how much time might they spend on those minor details, and is it worth it to maybe get from an A to an A+ in an exam?
Generally, I prefer my students to play the piece until they can usually play it better than I can sight-read... and I teach students all the way up to Grade 8.
Do you think that kind of fastidiousness is a mark of a good piano student? I'm partly asking because I tend to really let those things slide if I'm not interested.
I think you also need to weigh the potential benefit of learning say 2-3 entirely new pieces. How much time do you think it's worth spending practicing that last 5 percent in order to nail it?
Do you think the advice would differ for more advanced students, or perhaps while learning a piece for yourself?
I am inclined to think that studying few pieces really well is much better than doing many just to a so and so level. I never really got the point of doing en entire course book (at the time I used Aaron, but never did a whole book, we usually selected something like ten pieces from it) or an entire set of studies.