I was told about the benefits of this position about 20+ years ago by my martial arts instructor. She knew body mechanics, and was a shooter, but she didn't change me. She had multiple trips to Gunsite with Pat Rogers and Chirs Dwiggins teaching, and I bet she didn't do that there....I had just graduated an academy and was shooting Weaver by mandate and was coming back around to modified Iso. At the time FoF training was still not really new, but not really available, if only due to budgetary priorities. I worked with SWAT and Canine for years and even their basic schools with scenario training did not use Sims, or FoF, or do any real stress inoculation.
Fast forward to a couple of years ago, where FoF has become much more accessible and commonplace. I teach or take FoF/Sim classes at least once a year, and normally multiple classes. I took a Tac Med class with a retired SGM from SGM McPhee's former organization, and during a debrief, he told me that I turtled. He also told me that it wasn't a big deal, because when rounds start coming at you a natural instinct is "to get small, quick". He determined by watching me that my head was still mobile enough to scan and assess (most scenarios for the course had a couple of bad guys and several innocents), and address multiple targets (meaning my upper body mobility was good), and my hard break was in deed a hard break, so I had a view of my environment and was making decisions rather than locking in on one thing out of stress as I cycled through the potential threats in the evo. So I started paying attention, and when doing Sim runs, the higher the pucker factor of the scenario, the more I turtle, but I stay mobile, stay aware, and get my hits.
I do not train people to turtle. I don't like that I turtle, and when on a square range I do everything I can not to. But it is part of my body's stress response, and I am not sure that fighting it is the right thing to do. Maybe HCM's post attributing Jerry M on keeping your face flat is the key. Doing some dry draws here in the office have my gun coming up to eye level, but my shoulders are hunched (turtled) as my body develops a slight forward cant to get my weight forward on my feet and my shoulders slightly in front of my hips. (doing decreasing par time drills). My chin is not in, and I would describe it more as a goose neck than a turtle neck. I am thinking my targeting pod is flat...Maybe I will try to induce more stress on a square range and see where a timer puts me. It could well be that this response is slowing me down enough that competing in guns sports may take a bunch of deprogramming, or it may be slowing me down enough to accurately assess my shoots from no shoots before taking a decision to press the trigger, or it could be both.
I am pretty sure that I am far from Ideal, but things seem to be working for me now.
pat