It's Mamet's, let's say, directive a few years back to the writers of the TV show "The Unit," in which he reminds them, not subtly, what they must do as dramatic writers.
As we've discussed here before, fiction techniques work in nonfiction narratives. So there's a lot to take from this. For example (it is, in fact, written in all caps):
'LOOK AT THE SCENE AND ASK YOURSELF “IS IT DRAMATIC? IS IT ESSENTIAL? DOES IT ADVANCE THE PLOT?
ANSWER TRUTHFULLY.IF THE ANSWER IS “NO” WRITE IT AGAIN OR THROW IT OUT. '
I also love the fact that he used the word "typewriter" in this piece.*
*And also the word "dickhead" several times, which I use here in small type because this is, after all, a family blog.