Random thoughts to ponder on this.
Most adults learn best quite differently than high school, or even university students, which I've seen many times in my background in adult technical education (both in theory and in practice.) What one needs to do is find what methodology works for oneself, and it also depends on what you want to learn. Some people absolutely need all the pure classroom-like theory first, others not so much. Not all institutions understand this, nor do all instructors, and it can be very frustrating to learn in a manner other than what you need. I've been learning to sing lately, but did not respond well to classic methods of teaching.
Music is perhaps the most beautiful physical expression of math; to me the two are inseparable. It depends on how your brain works. Music is all about patterns and spacing along a number line; there are only twelve keys/notes in an octave, everything just repeats after that, at least in Western cultures. Scales are merely repeating numeric patterns. Thinking of the notes vs numbers does not doom one to being a mechanical, lifeless un-knowledgable player by any means any more than being highly educated in musical theory makes you a good musician. And transposing becomes much more intuitive, almost simple.
Favorite quote: "In theory, theory and practice are the same; but not in practice."
Consider that you don't have to understand the physics of gyroscopes to ride a bike (which is actually an extremely complex learning task); nor does understanding the physics mean you can ride one, but at least you'd understand why riding a two wheeled conveyance is very counter-intuitive.
Unlike linear instruments like the piano, stringed instruments may have mostly notes that can be played in multiple locations, which is a big difference practically applying theory, even though the same basic theory applies. These overlapping patterns add another layer of complexity to learning.
On the other hand, if you really want to gear up on practicing your theory and playing and how it all relates in real time, get yourself an electric spinet organ with two keyboards and foot pedal, and learn to play melody with harmony with one hand, chord structure with the other, and keep a walking (literally) bass line going with one or both feet. Or try a pipe organ. Using two different scales. I took lessons on those for many years as a kid, and wow did that ever pay off when I picked up the bass at 50, 13 years ago, but NOT in the ways you'd think! However, bass guitar is far more intuitive to me when thinking in numbers and patterns.
