For me, it depends on the student. If I think they will get discouraged from playing if they stay with a piece too long, I'll pass it, and work on the same technical difficulty using some new material. Mind you, all my students are still in grade 0, having not even played a year yet. And they are quite young, too, so I focus more on fun, than perfection. My teacher on the other hand is a different story. I will probably spend a few months on a piece that I'm learning for fun, but EXAM pieces, well, let's just say, nine months and counting, but only two more weeks to go!
Hi, I am a student and i wanted to ask teachers on the teaching board about what you expect from a performance of a piece learnt by one of your students in order to make sure it is finally accepted (ready for performance).My teacher just doesn't seem to accept anything from me, even if i played some piece crystal clear, she tells me i have some problem at some part (dynamics, tempo..etc.)I feel it is like an endless circle. Everytime i go to the lesson, she tells me you have to do bla bla in this piece and bla bla in that piece. I have never learnt new pieces since about 2 or 3 months.
For me, it is great to prepare a piece months and months, but this luxury is rarely given to us later in life.