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.