This was my hardest set, and this is why I believe I reached true failure:
For years I believed that reaching failure meant feeling burning, pumping, or extreme discomfort.
Today I understand that was just fatigue and self-doubt.
In this specific set, I didn't quit because of pain or fear of "not being able to do another rep."
I continued to the exact point where, maintaining strict form, the muscle was unable to produce any more movement.
There was no cheating, no swaying, no acceleration: just total control and maximum effort.
That's when I understood the key difference:
Before, I stopped when I wanted to stop;
in this set, I stopped when the muscle decided to stop.
That moment changes everything.
Because it's not uncomfortable: it's definitive.
And it's only then that the stimulus is sufficient to demand real adaptation.
This reflection made it clear to me that most of the time we don't fail due to a lack of strength,
but because we quit too soon.