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.
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.
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.
I don’t see how that could lead to a credible proof, even on the balance of probabilities.
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.
Otherwise your comment doesn’t make sense.
Or is that meant to be metaphorical?