In one of the monthly writing groups I lead, Molly mentioned that she was working with a writing buddy who was making a lot of specific suggestions. She liked the buddy's suggestions and so had turned her efforts to polishing the stories she had already written, rather than continuing to draft new material. This sparked a very interesting discussion in our group about when to draft and when to polish.
I've come to believe that it depends on what kind of editing and polishing we're talking about, and it depends a bit on how experienced a writer you are.
The two processes are different. Drafting requires a level of thinking, mulling, imagining, arguing, feeling that editing does not. For many of us, this is why it is so much fun. But it can also be scary for this isn't about control but expansion, it isn't about perfection but about making a mess and maybe even some big mistakes that will have to be undone.
For myself, I do rework some things when I'm drafting but they have to do with content. Like this morning, I couldn't remember if I'd made it clear that Cassie was a redhead and I wanted that identifying characteristic to be enough for the reader to know who had been in the accident. So I went back and reworked the physical description of that character the first time we meet here. I could have made a note to do it in a revising or editing time, but it seemed simpler to find it and fix it while I was thinking about it. Then I scrolled back down and went on with the scene. When something seems to be part of the content of the writing, that falls into drafting for me.
Editing is about grammar, punctuation, word repetitions, clumsy sentences, saccharine sentences, style and mechanics issues. And that's left-brain, what's-the-rule kind of work.
I don't recommend mixing these too closely. It's too hard to do a good job on either one if you're trying to do both at once.
In Molly's case, I was concerned that she would fall into the pit of perfection, of getting one story just right. That's not a good way to write a book, or learn all the many marvelous things there are to learn as a writer. Instead, most of us need to keep drafting for a good, long time, and then turn to the editing side of ourselves.