Something I find whenever I run a more traditional kind of RPG is that things never take the time I expect. The scene I expect to last 5 minutes lasts for an hour, and the stuff that I think is going to take an hour is done in 30 seconds.
...it occurs to me that the biggest reason this doesn't really happen in more freeform games is because you go into them *without* any knowledge of what the scenes are actually going to be.