How to practice piano

I've discovered practicing methods, none very original.

I set the timer for 30 minutes and practice one page of music, or an hour as the case might be. If you can't make progress in this amount of time then the piece is too difficult for you. Once you now the piece then you can still practice it for an hour at a time. It is great self-discipline. If I feel the need to play something else then I do for a few minutes, then go back to the task at hand.

I also slow it down quite a bit. You can play a piece four times slower than its eventual tempo, or as slow as humanly possible if you want.  

I play the parts that are easy, or that I already know, only a few times, and spend the majority of the time on the difficult parts. I start playing the piece at different places, not from the beginning each time. I sometimes start at the end and work my way backwards. I practice hand separately.    

I play along to a recording of the piece.  Etc...  I doubt I will discover a genuinely new trick for practicing.