Since I've become an Editor with Anaiah Press, I've had to partition my time. Although, it's not just about time management, it's a completely different mindset. When I'm in "edit mode," I can't easily switch into "drafting mode" for working on my own book. It's like I have two different brains, which I suppose I do if you count the left half and the right half.
When I'm in drafting mode, I have to immerse myself in a space. I let the images flow from my head to the keyboard with little interference about what came before, and whether I have too many of the same word, and all that itty-bitty stuff. If I paid attention to every detail, I'd never get a single word on the screen.
Drafting is also like listening to the character's voice in your head and just letting it come straight out. Sure, it's not perfect, but it doesn't have to be. That's exactly why it's difficult to draft when I've put my edit brain on, because editing requires me to make things as perfect as they can be.
When I'm editing, I'm extremely picky. I won't let unnecessary passive voice slip by, and I work to make sure to vary sentence structure, word choice, opening words/phrases, sentence length, and all those little things. Not only that, but I have to pay attention to larger plot points, character emotion/growth, foreshadowing, subtext, and scene strength. There's a lot to hold in your mind when you edit, and if you do all that when you draft, you'll murder all the creativity.
The real deal is that drafting/writing is a right brain activity. It's full of creativity, sunflowers, and rainbows. You can't put rules on it, or it stunts the growth. If you're too restrictive, you won't find a voice which is the most important thing for connecting with the reader.
Editing is a left brain activity, logical, rule-centered, and detail-oriented. You have to be rigorous to catch all the little things, make it shiny and full of polish. Rules win...except when they don't.
This brings me to the important lesson...balance. When editing, it's easy to get so technical that you destroy the very beauty created in art of writing. The real art is balancing how you follow the rules, with how you break them. Because sometimes you've got to use passive voice, and sometimes you've got to tell instead of show, and sometimes that fragment in the middle of a paragraph is needed. It's all about balance.