There's no real point to either. Magical energy's pretty much omnipresent in the world, and unless you're humanity's greatest magician casting something capable of leveling a landscape, you're never going to be like "damn I'm out of magical energy". Magic's more akin to a school of research than anything else; ability in magic is fostered by understanding, not by having lots of magical energy around. 

There's lots of air around me and outside of very specific circumstances, I'm not gonna be needing more air than there is around me. At the same time, having a fuckton of air around me doesn't mean my breathing form gets better. I've gotta learn how to use my diaphragm and shit for that.