I think the editing-after-the-fact objections mostly come down to a matter of consistency - we're all linked to a poll, and there's a sort of expectation that what one person reads by clicking through from the poll is going to be the same as what another person reads. To make substantive changes to the thing is to present something different, so people are judging and making voting calls based on a work that is very much in progress, and they may not know that. I think most people assume that if they get to a piece from the poll and then click back the next day there won't be major changes, and that everyone is seeing the same thing - if voters on the first day and the last day are reading different versions of your entry, it can get kind of confusing, you know?

I'm all for the creative process, but I try to get the best work I can out during the time limit stated, and then leave it alone until after the voting is done. If I think of something awesome that needs to change, I might mention in comments ("hey, I had this fantastic idea.." or make edits to my personal, local copy, but changing the version that's online and live seems disingenuous to me, personally.