I'd agree that it is worth pushing your limits during training, but the best-case scenario during actual conflict is to be as close to 0% overwhelmed as you can be.
Overwhelming an enemy involves getting inside their OODA loop. I can't see a real life-or-death scenario, outside of training, where you'd want your enemy to successfully get inside your OODA loop and disrupt your flow and rhythm, even for 0.1% of the time.
You of course don't want to become comfortable and complacent, risking losing focus, but there must be better ways of avoiding that other than being occasionally overwhelmed.
You’re suggesting there are real deadly combat scenarios where it is beneficial to have your OODA loop compromised. Ok maybe you’re right, given the infinite possibilities.
But until you can present at least one such example scenario, no individual would be willing to take such a risk when their own life is at stake. Real combatants might value the motivating threat of being overwhelmed, but do not actually wish to be overwhelmed (i.e. have their OODA loop compromised).
In deadly combat, no one is looking to theorize. No one quibbles about their inability to prove the negative. They just want to live to see the next day.
My belief doesn’t matter. Without proof that it is advantageous in a given scenario, I would never prefer to be overwhelmed in deadly combat. And I doubt you would either. If you believe you would, please present an example scenario.
That would mean leaving some performance on the table the rest of the time.
It doesn't seem clear at all whether one outweighs the other.