The Adjective Fallacy is trying to learn by mastering the formal rules. Just because a concept can be rigorously defined doesn’t mean we should study it that way.
We didn’t become good at English by studying a chart: we developed an ear for the language and know how it should sound. And “old little lady” sounds off.
Similarly, getting good at math doesn’t mean marching through a gauntlet of rules on every problem. It’s having a native speaker’s feeling about what works or doesn’t.