Drafting without revision and revising once is the fastest way to write, but not the only way. Some writers, sometimes including me, produce multiple drafts, which is inherently slow.
Some writers stop in the middle of gathering and whip out a quick draft to find the holes in their knowledge. Then they devote the rest of their gathering to filling those gaps. They don’t necessarily produce a new draft later, but sometimes the added information requires an entirely new version.
I sometimes draft three or four unrevised paragraphs to see if I’ve got the tone right, and I usually delete them. Some writers use this technique to design an appropriate beginning.
I only know of one writer who uses the following method. A humor writer types over 200 words per minute on continuous butcher paper rolled into a typewriter. She figures out what she wants to say, then types at top speed until she runs out of steam. She then discards the entire draft and takes a long break. Then she does it again, and keeps repeating this cycle until she types the bottom sentence. Then she revises, just a little.
Speech writers often write a full draft and submit it to the speaker to see if it says what’s desired. Often it doesn’t, and they start over with a new draft. (My wife Joan once worked for a speaker who would reject an entire draft with a red slash across the first page or a red “NO” at the top. She had no idea what was wrong or right.) This slow method works better if the writer interviews the speaker briefly to find out what he wants to say, and then drafts that.
Sometimes a draft is such a disaster that it can’t be revised, especially if it was composed by multiple authors or a committee, or by combining disparate documents. You can try to revise it, but I find that having one writer produce an entirely new draft works better. You get there faster, and the various authors are less likely to try to defend the parts they wrote.
Finally, some authors write multiple drafts because they don’t know any other way to compose. That’s slow, but fine if it works for them. If you must do it that way, don’t revise as you draft; otherwise, you discard things you spent time revising. As a coach, I often advise such people to spend more time organizing so the first draft gets closer to what they want to say.
[What kinds of multiple drafts do your write?]