I don't like being told that's where you, you know, if you walk on set and somebody was "okay, you're here and you're going to walk over there on this line." And my reaction is always how do you know? How do you know that's what I'm going to do? How do any of us know?
There's very few directors that know what that rehearsal's for. And often it's just about calming down the director. If he could see it or she sees it, she goes oh, it's going to be okay.