Training wheels/ breath marks. Sounds like fightin‘ words!
Nothing could be further from the truth.
Measures on a tank of air? Equally juvenile.

We have to inhale in a way that lets us exhale without having to release „compression“ or „expansion“ muscle tension first. One of the major flaws in tanking up for maximum measures is that we create tension that we have no routine to remove musically for.
Yes, we can expand breathing capacity. That involves an organized, prepared body, no brute force!