Quote Originally Posted by consentingadult View Post
This is how I see many rationals as well. I used to have an LSE friend who I used to call on Friday evenings asking "What are you doing tonite?", he'd typically answer "Uhhh, nothing, just watching TV". So I would ask him if he wanted to join going somewhere, and he never ever accepted. If, however, I would ask him 3 weeks ahead, it would pretty much always be a yes.
I probably act this way, too. If I've settled down comfortably, made some popcorn, and started watching a good movie, I'd be loathe to interrupt what I'm currently doing. On the other hand, if I weren't doing something particularly engaging, I would be very open to suggestions of doing something else. It's not so much that I need to prepare for something, but that I don't want to interrupt an activity in midstream. Consequently, 2 hours' notice is almost always plenty, and even no notice at all is fine in some cases.

Edit: obviously, I can interrupt an activity under certain circumstances. If the house is burning down, I don't need three weeks' notice to evacuate: I'll put down whatever I'm doing and leave, like any sane person.