On the fretting hand, I mean, of course.
I do about 98% of the time, I reckon because I started out on guitar ...
I do not have large hands, what I am told makes it even stranger, but I find it's how I learned/taught me, and it's baked-in.
Anyone else do this?
Anyone used to and change, and if so, why?
I mean, I play a good few hours a week, sometimes a day, for a few years now, and I've had no physical problems yet ...
I find that over the years, without trying, I've developed a smoother technique (even if nowhere near fantastic yet, much room for improvement no doubt). When I started out my fingers flapped about a lot... while now they stay close to the board and move little. Similarly, thumb-over is something I no longer do, because it hinders smooth playing. I didn't consciously change, I just found one day that I wasn't doing it. I imagine it depends on what you play. If it works... it works! But if you find that you're not agile enough for what you want, that would be one thing to work on a little.