Every pianist has their own way. I have atteneded many of Ashkenazy's master classes but I have to say I find how he sees music a little strange. For instance if you listened to him play Rachaminov Prelude op32 no12, you would say, how damn fast! Too fast, you can't really appreciated what has been written, then listen to him play a Scriabin Prelude, Op17no5 for instance which is marked Prestissimo, but he plays it slower.
But then again Richter made heaps of critics shift uncertainly in their seats when they hear how he alters tempo in Beethoven, so I guess there is no right or wrong, only what is traditional and not.
I have to say that his musical memory is encyclopaedic, the amount of music he has recorded and discs to his name is phenomenal, he is very very hard working and dedicated musician and that is what has made him such a big name.