Is "every last ounce" a common expression? Is it focused on "even a little bit of anger" of "the last anger you may have"? Why is this used here? I know it's for emphasis, but which aspect is it more focused on?
ex)It's natural to believe that external events upset you.....No matter how unfair others might appear to you, they do not, never did, and never will upset you. The bitter truth is that you're the one who's creating every last ounce of the anger you experience.
It means all of it. "Every last drop" is probably a more common expression. In this case, it is saying that not even one little bit of one's anger is the fault of someone else -- it is all your own fault, every last ounce, every last drop, every single iota.