I've never been to a gym where you're assigned a locker for the day (or given a key). Either you have one permanently assigned (rare) or you go in and find one that isn't occupied.
Logistically, it makes sense for them, as it presumably cuts down on maintenance and cleaning. But it is super-annoying to squeeze past several other sweaty folk when there are two entire locker corridors empty and adjacent.
I asked them about the latter issue, and they said that it might get fixed next year; but there are years-old Google Reviews of the gym citing this promise!