It is a mystery

I always wondered about rinks' prevailing direction as well, but I guess runners always go one way on a track, and speed skate races always go one direction, so. Roller derby is all also done one direction, but our practices always, always, always included a lot of opposite-direction work because we'd wind up with such huge repetitive-strain issues from unidirectional work-- for years I wore thigh-high socks at two different heights because of the difference in size of my thighs, though I think that after five years it's finally gone away. My calves were different sizes too but not as noticeably. Where it really got me was my back muscles-- nothing visible, but my lower back was extremely uneven for a while and I wound up with a lot of pain trying to fix it. (And I tore a muscle, at one point, so. Don't do that. Don't recommend it.)

A big thing that can help too is to skate backwards. If you master forward-backward transitions, and wind up stuck at a skate session where they won't reverse direction, you can work on backwards skating for a while and it strains your back the other way, at least.

(The other thing is to do off-skates work to strengthen the hip and thigh muscles. I hated them, but lunges, walking lunges, squats, and abdominal work all really contributed to helping me master skating.) Possibly, though, the abdominal stuff was because I have uh a lot to counterbalance and so my back was always what gave me trouble when I was skating-- for my entire career, I suffered from back pain while skating and those were the first muscles to get tired, and where I suffered my worst injury, before the uh epic double ankle sprain that had nothing to do with skating but ended it anyway. But for most people, the limiting factor was thigh muscle strength, so you literally cannot do too many thigh-strengthening exercises.)