I’ve recently been made aware (by my very smart daughter) of the fine distinction between “knowing” and “understanding.” They are not the same thing, and the presence of one does not guarantee the other. For instance, knowing how to analyze a sentence is different from understanding your native language; I couldn’t tell you what a “prepositional phrase” is, but I suppose I use them in my writing. I’m sure there are folks who know all of that stuff really well through the school-preferred method of rote learning, but still lack the understanding to put words into coherent and interesting forms. I would imagine that the majority of professional writers (of which I am not) know and understand what they are doing.
The same can be applied to music (and thus the banjo) of course. Do you know your scales? You probably don’t, but I bet you understand them more than you think. Do you listen to and like “Western” music (as in “music from Europe or America”)? Then you understand your scales! That music represents your “native language”; music is literally made from them, so of course you do! If the scale was different, the music would be different, which is a good explanation of why you don’t understand Indian music, for example (unless you have studied it and know how to understand it).
You could say that a “natural” musician understands music, and that a “learned” musician knows music; either way, they get the job done. I propose that the very best musicians know and understand! Figure out which side of the coin fits you the best, and then spend some time investigating the other side; you can’t help but improve!