When someone's curling in the powerrack, I'll use the open. But if somebody's in that, I'll literally go up to the curler & ask for the rack, because I need to squat and literally every other location in the gym he can curl. It's usually oblivious young kids who seem kind of scared when you call them out. I'm not mean about it, but I make it pretty clear that common sense dictates I have priority here. They either leave then or grab a final set shortly thereafter, & the world is in balance once more