When you think about it, it's a good thing they have a time limit. It takes a very good storyteller to get their BIG idea across in a small time frame , I'm sure they have the limit on to enforce this idea. As always quality over quantity, animation is pretty grueling I don't think you'll have the time to do something too long, or over ambitious. You wouldn't want to start getting your hands dirty only to realize your only going to be able to finish it half way. Plus Murphy's Law comes into play, from my experience Maya's a B***, you'll need some extra time just in case.