That specific hypothetical seems like a lot of book keeping. I imagine there are be better solutions for the problem you mention in the following post (maybe take 10 and take 20? I'm not 100% convinced on those)

As for the concept of stamina, I have been fiddling with it as a substitute for HP, to show how one's ability to stay away from danger slowly is reduced. It can also be useful to fuel abilities and easier to justify regaining it.