I just wanted to add that Heinlein may have been referring to the publishing process rather than the drafting process. I'm an editor myself, and the one thing that authors really deserve to be shot for is changing their submitted text at the same time as I'm editing their submitted text. This results in two versions, and it's impossible to resolve conflicts and amalgamate changes without a truly enormous investment of time.
Depending on how strict the publishing house is, a portion of an author's advance or royalties may be clawed back to pay for this extra work. Alternatively, the author's revised text is simply thrown out, so they've only wasted their own time.
Also, at the time when Heinlein was writing, considerable editorial input was much more common for fiction. Now, publishers and editors take a comparatively 'hands off' approach, focusing more on, for example, obvious logical errors for a murder mystery and grammatical mistakes. Phrasing and structuring is largely left to the author. Heinlein could rely on a great deal of input from an editor - what's the point of changing something if an editor will ask that it be changed again?
As for how this relates to the OP: I think that, although everyone does write differently, the best hope that you have for limiting your writing time would be to write your first draft with minimal revision and interuption. It is hard, but personally I think it relates to GTD in that you need a method to keep track of any issues and get them your mind. It won't work if you're afraid that you'll forget something when you go back over the report.
One trick that I often use is to type "tk" next to a fact that I need to check or a phrase I want to rewrite. You can use the 'find' function in Word to find all instances of "tk" in a document - it's not used in any English word, so you'll be taken to all the checking/revising areas. I also find the comments feature really useful to note down anything that requires more than a simple reminder. Some people find keeping a paper notebook is more helpful to keep freeform notes.
The only reason this might save you time in the long run (as I agree with others, any time benefit would likely be pretty marginal) is that you can more easily justify your time to your superiors when it's clearly broken into sections. You can show them drafts and let them see explicitly how much work is involved. If you wanted, you would be able to create a case for outsourcing the revision process to a freelance editor or another staff member.
Heinlein didn't need to rewrite, but every other author I've ever met or read about did.