Good question, Brit. I think some stories need to be paced more carefully than others. Like, if the "fun and games" are fun enough, who cares if they last a little longer?

I saw The Exotic Marigold Hotel this weekend. Interesting to work out how the beats happen for an ensemble cast... But they did happen. Every story line had its All is Lost moment at about the same time, with events threatening the community they'd built together at the hotel. But two characters exit early, and their departures act as catalysts for everyone else's Dark Night of the Soul.

So I would say that of course there's some flexibility, depending on what the story needs. But for me, having been rejected once too often for not having a strong enough plot, I'm not going to stray too far from it until I've got a better handle on things.