Editing
As a short form writer, I know that each word is chosen with extreme precision. While at a summer writing retreat, we did an exercise: whatever word count your piece was at, bring it down to 300, then 250, then 150, and so on, switching to increments of 10 and then 5. Once you got to 5 words, or even a single word you were hard pressed to decide the core of your piece. But that's what the exercise was meant to do: cut through the fluff of your story or poem and think of what you were truly trying to convey.
As others have already said, I agree that Prose needs a better editing system. But I also kind of like the blank format, and the vulnerability & trust that quick writing and next-to-no editing provides. My rawest work tends to come out of Prose, mostly because I'm not really censoring myself. Just as I'm about to post this without reading it over once. :)