I've had the good fortune to take a number of "structure tactics" classes despite being little more than a Joe Schmo. These have included AIT and UDC with Paul Howe, shoot-house with Joe Weyer at Alliance Police Range, Force-on-Force with Practically Tactical at Alliance, and the aforementioned AMIS with Craig Douglas, held at a derelict school in Pittsburgh back in 2016.
ALL were stressful, ALL were great learning experiences. No class that I have EVER taken was more mentally exhausting than AMIS. I still recall sitting down in the hotel after Day 1 to write up some notes and passing out with notebook on my face and all the lights in the room still on.
In my class, there was SOME use of what the OP seems to be describing as "compromised shooting positions" (although, in the video he linked to, I really don't see any compromised shooting positions....since when does shooting one-handed=compromised???). These were mostly used in situations where we could, due to angles of exposure, get the drop on someone and hit them before they could hit us. So if we were flattened against a wall and, due to angles, could see the adversary's foot, kneecap, elbow, whatever, and he could not yet see us, then it was worth it to be able to get a hit on the adversary. Not to sound like a dork, but John Wick does that in the first movie, hitting what the bad guy gives him (foot in that famous nightclub scene). Usually the ranges were quite short and so shooting one-handed was not much of a handicap. Most of what we did was constant adjusting of the two-handed grip, pulling in toward the chest and pressing out, as the situation dictated. And, of course, when we got to low-light and borderline no-light, your light set-up had an effect here (handheld vs. WML, etc.).
As for the cover/concealment issue, I think experience has shown and countless CCTV videos have shown that people TEND to shoot at what they can see, and shooting through walls is rarely done, even by the bad guys (at least in a non-MOUT, more stateside context). I've seen shootouts in clothing stores where people did NOT shoot at their opponents through clothing racks, and instead waited for a visual target.
If you want to read more about my experience in AMIS, feel free to read here:
https://civiliangunfighter.wordpress...a-49-410-2016/