Premature Submission: how to know when your work is polished and ready for publication

Twice now I've had my work accepted by literary journals via contests I entered (and didn't win). And both times I found myself in the awkward position of explaining to the editors that I'd since revised my essay and asking if they would still accept it. Luckily, both times they said yes.

Actually, the first journal mistakenly published the original submission, but it was just as well... although I'd tightened sentences and reworded passages--and even removed an entire section--I admitted there were parts I liked better in the initial version, and nobody would know the difference. But I'm keeping my fingers crossed that the second publication (this spring) prints the polished revision.

All this to say that revising work post-submission (or submitting prematurely) is not something I'd recommend making a habit of. But this snafu brings up the question of how we know when a piece is ready for publication. In the case of a book, agents and editors often work closely with authors who may revise their work multiple times after acceptance. But when you're sending an essay or short story out, it's generally a one-shot deal. So it had better be your best.

Here's what Michael Nye, managing editor of the Missouri Review, says this about premature submissions in a blog post called "The False Promise of Acceptance and Publication":

Publication and promotion, while good (of course) and necessary (definitely), pales in comparison to getting the story right. The apex of the writing process is before an editor or agent has seen your work, when you have the satisfaction of knowing you’ve gotten it right. Once the story is in their hands, perhaps well enough to be published but also perhaps prematurely, it is out of yours. 

I recently finished a third revision of an essay I submitted to several journals in February and will continue to do so in March. I haven't looked at it for a week or so, but I'm pretty certain it's the most polished I can get it. I've got mid-March deadlines for another essay, but I'm nowhere near done--it's still struggling to find its structure, its focal point. I read through it tonight on Scrivener and feel completely uninspired. Whereas the last time I worked on it, I was pretty excited about its content and voice, now the critical voice in me is asking, "What's this really about? How is this compelling? Where is this going?"

Submission and contest deadlines are great motivators, but we writers need to be careful not jump the gun. Can I really get this piece in shape in 7 days? Doubtful. I'll be disappointed if I don't, because I have certain thematic issues in mind, but at least I'm on the road to completion, and if that date turns out to be the end of the month (or beyond), so be it.