When playing or practicing I always keep my hands on the keys. I never lift up or bounce around. I was practicing yesterday and my step daughter brought it to my attention. I never noticed it before. My hands are almost flat and I never bring my hands down in any rush to play anything. I bring the hands down to the keyboard then begin to play. What are your hand positions when playing and how do you find them beneficial ?
To me, posts like this illustrate the difficulties and pitfalls in trying to use words to describe technique.
It seems virtually impossible to always keep hands on the keys. That would require sliding along the keyboard while the fingers are touching the keys. In addition to being impossible, all good pianists lift their hands off the keys when there is some free time and under many other circumstances. Also, if the piece is difficult not rushing to play some passage or notes seems virtually impossible. Of course, maybe the OP means something different from what most would mean by not rushing or keeping hands on the keys.