My job involves a lot of editing the writing of technical experts, for whom I'm a sort of communications gatekeeper so my small organization is coordinating properly with our parent organization. Even in the role of proofreading others' writing, I won't try to go from initial draft to finished product in one pass, because I know that the initial errors will wear me down too much to catch the ones later in the document, or to catch the more holistic problems with what's written. Point being, the act of taking initial ideas from your stream of consciousness to the most complete and accurate portrayal you can offer is extremely iterative, and no one should feel bad about dumping a whole bunch of half baked concepts onto a page when they're starting a project.