Exertion Threshold?

I’ve noticed something lately, and I’m wondering if anybody else has experienced the same thing. It may have another name, but for the sake of this post I’ll call it the exertion threshold.

What happens is that there is a point where a certain amount of physical exertion results in a sense of satisfaction. Anything less seems unsatisfactory and just plain empty.

I first noticed it doing a cycle of 3x10 Waterbury style. 60% was O.K., 70% felt good, but 80% hit the mark like nothing else.
The same sense has since carried over to max effort lifts. Even when they aren’t personal bests, there is a drive to hit a certain point of exertion or be left feeling empty.

Does anybody else get this? Is it a relatively common thing, and I’m just late to realize it, or what?
I want to throw this one out there to see what others experience with it may be.