When your characters want one more draft

The idea I'm currently working on fleshed itself out in book form over a year ago. I think it was last May. I wrote the entire first draft in seven days. How very Hemingway of me :). I then put it aside and sat on it until last month. After a year and a half I thought I was ready to tackle that second draft. I had a better idea of who the characters were, where they needed to go and how they needed to get there. The meat of the story is still true but the direction, the road was under heavy fog. For a month I've been working tirelessly on the second draft. Thursday I was at the point I thought I was ready to plow through to the very end. Then... Something tugged at the back of my mind. It was a concept I'd put in the original draft, a concept I thought needed to be taken away, to streamline things. The problem is that concept won't leave me alone. It seems to be a very integral part of my character. It makes her more interesting, more grounded, much more three dimensional and, quite frankly, waaaay less Mary Jane. The problem is that it will require a draft I wasn't planning on. This draft, number two, was to be the one before my Crit Partner Draft, you know, the one you send out to those trusted souls who put up with your ramblings and agree to help you edit. Well, that is not to be. I could let this part of my character go but I fear if I do she won't be who she wants to be, who she needs to be for this story to carry itself to those fabled words The End. Not only that, this book sets up a second story - unconnected - that needs its roots to be firmly founded here and now. Though the stories aren't a series, the subject matter is similar and is required for a third book that will bring these two full circle. Sounds confusing, yes? Maybe it is, but that's the way my stories come to me. Confusing and cyclical. Always cyclical. Let me ask you: how important is it to YOU as a writer to take as much time as you need to make the characters who they WANT to be as opposed to fleshing out the story in the quickest and (for you) easiest way possible? I don't want to cop out and I'm not talking about laziness. I'm just curious. I know what I have to do (write more drafts!). Have you ever had this problem? Happy weekend everyone!