I just spent an hour watching a 1980 video "David Mamet: The Playwright As Director". It's 27 minutes long. I watched it once in order, once out of order. Mamet coaches Lindsay Crouse and Michael Higgins in scenes from 2 different plays. Crouse was married to Mamet at the time, but they don't breathe a word of that in the video. Mamet also directed her in House of Games.
I find Mamet fascinating when we writes about the theater, but I've noticed that his directing actually irks me, because he seems to flatten the feeling out of his actors. In his favor, he keeps a strong "in the moment" sense of real interaction between the actors. So at least you have something interesting to watch.
In the video, he keeps telling the actors not to "add anything", other than executing the play's actions and reacting to the other actor. He tells the actors that this "mechanical" approach will relieve them of the responsibility of feeling-on-command, which Mamet views as a crazy-making burden.
It's almost as if, as a writer, he doesn't want the actors explicating his cryptic script with all that emotional diversion
Which can leave the audience reeling.
So he resists the incursion
Of another artist's feeling.