One of the professors at my university is a big advocate of avoiding spending too much time perfecting each musical element of a piece. Rather, he says, one should have the technique to be able imagine as they play, while freely transferring your imagination to the piano. So, one should never really play the piece exactly the same every time.

I think Valentina actually has a more flexible approach too playing her pieces than most - just look at the different renditions of Rach's op. 36 no. 6.