There are no hard limits either way, but keep in mind:

1) As with all other exercises, the requirement is to spend at least 15 minutes working on it. We obviously don't track you via Zoom like your boss does, and you're only cheating yourself if you cheat that, but contest round judges will probably figure it out if you didn't put in the effort.

2) In the other direction, a story that's too long might test a judge's attention span.

In other words, it's not about quantity, but quality.