I get your point but also I'm a pedantic Lemming, so I want to point out that in the middle-ages, castle would purposefully build uneven steps. People familiar with the castle would soon get used to them and they'd be no bother, but an attacker running upwards will surely trip. And they'll trip because of the stairs. Or will it be their own fault for not looking at each individual step to give your body the information it needs?

Just rhetorical exercise, I don't actually care at all about one side or the other.

(An added stair fact, round staircases would ascend in a clockwise manner, so that right-handed defenders would have the advantage over right-handed attackers whilst fighting in the stairs.)