In order to become a professional pianist, one must practice alot. But what I don't know is what do we have to practice? I mean, we can practice scales, arpeggios and stuff to improve.. But certainly we don't play them for hours right? And does practicing mean playing compositions for hours? I need some tips on what and how to practice for hours.
At intermediate stage polish a few pieces to a high degree. At a higher stage unless you're sightreading it's annoying not to.