In exercise culture, the word failure has a particular meaning: keep going until you absolutely cannot do any more.
Without specific parameters, this is a wild notion (as in lacking restraint) that is romanticized too often. Statements like "I train to failure" are made more as status signals than they are reflections of a specific exercise approach.
If they were the latter, of course, nothing would need to be said.
Wild failure in exercise leads to injury, inconsistency in performance and noxious, expletive, disingenuous exercise displays in gyms everywhere.
However, putting parameters around exercise failure can be like a magic ingredient in your progress. The parameters need to be informed and thought through carefully for the failure experience to be productive.
When this happens, it is quiet, subtle and revealing of abilities you like never imagined you had. In fact, this literally just happened for a client of mine about 15 minutes before I started writing this.
Properly tamed exercise failure might be the realization of your deep physical potential.
That really ripples.