This is actually not stupid.
I also laughed when I first heard about it (5 minutes ago).
We focus a lot on managing time. But there are other finite resources we have to manage within each day.
You can only spend so much of each one before becoming exhausted.
Spoon theory deals with one of these things - physical energy. And the article is well explained. So it’s a good introduction to this kind of thinking.
You can go much further in this thinking than the article. Think about management. You normally assign tasks to whoever has the free time. But people have different amounts of patience to spend each day. So if one of your people has a lot of patience, you should assign him the task, because he can spend a lot before running out.
But if you have two tasks requiring a lot of patience, that guy might run out. So you assign the second task to someone else.
It’s basically very intuitive. But it’s helpful to think about it the same way we think about time. To quantify it.