Handwaving can be a very useful GMing tool, although if you do it too often, there’s not much point in playing an RPG at all.

I’ve handwaved chunks of past sessions for a range of reasons: time constraints, because my players were (or seemed) bored, because I made a mistake, and needed to ensure an encounter went a certain way, because I realized something wasn’t going to be fun to play through, etc.

There have also been times when I should have handwaved something, but didn’t — and that’s the sort of judgment call where it’s very useful to hear how other GMs approach the same kinds of situations.

So how about it: Do you have a hard and fast rule about handwaving? What kinds of things have you handwaved? What handwaving opportunities have you missed?