When is Enough Editing, Really Enough?

I’ve been working on the same WIP, no the same prologue for almost two years now. I’ve entered it in contests and got critiques. My crit partners have bleed all over my pages and it was even critiqued by an agent. All had great things to say. And with every critique I made changes. I thought it was almost finished. In fact, I had a writer friend look it over and she said it was excellent. Then I took the opportunity for a free critique by another writer/critiquer friend and it was obvious there was still room for improvement.

Now, I guess this WIP will be marked as the major LEARNING WIP because I am learning so much. But I’m wondering, will it ever be ready to get published? Honestly, I’ve seen some pretty bad fiction published. They could have used a dozen critiquers to help improve the prose, but when is enough really enough?

I love the new edit I just got and I made some great changes already, but when will it be ready to be sent out again? It’s been rejected by many of the big houses, so obviously it wasn’t ready. But when will it be, and when will I know?

Being a writer can be so frustrating at times. I want to learn, but in my humble opinion it takes a lot of money to learn. I’ve already spent probably a couple hundred (not including conferences) on this one WIP, and it’s still not ready. [shaking my head] It’s really enough to make me want to through in the towel.

But I can’t. I’m a writer.

[Sigh] So what’s your opinion? When do you shelve your WIP and move on. It might be easier for me if I didn’t have such conflicting opinions about my WIP! If I knew it absolutely stunk, I’d shove it in a drawer and lift my hands in defeat. But two years on the same prologue? I haven’t even finished the WIP, yet. When is enough, enough?