Creative writing people, echoing Annie Lamott's advice in Bird by Bird, recommend writing "shitty first drafts." SciWrite professor Kristin Sainani said something similar:
My biggest tip for the first draft is don't be a perfectionist. A lot of scientists are perfectionists, and they want to get it right on the first try. But writing is not the place to be a perfectionist, especially writing the first draft. When I write a first draft, my goal is to get down my ideas in complete sentences, that's the bar I set for myself. Complete sentences, in order. And that's it.
In Dream Song 54, John Berryman said, "Write as short as you can, in order, of what matters." And that should apply to any draft, from first to final.