Having learned theory at an early age I never questioned its usefulness. The ability to identify chord progressions and modulations made sight-reading easier and saved a lot of time in learning music.
Now, in my maturity, I find it incredibly challenging to go back over music of which my over-theoreticized brain had tired, seeking now its integral sense rather than imposing on it the time-saving simplifications of a pressured learning process.
Specifically in relation to Schubert's A minor Sonata, Op. 42 (1825). I realized today that I know so much information about G-sharp's predictable function in relation to A that I haven't allowed the tone to exist on its own, without necessarily leading to A. Thus, when it turns into A-flat a lot of the mystery has been diminished, if not lost.
This sonata is particularly interesting in this regard because the predominantly white-key environments of A minor and C major (the second movement) put the black-key pitches in high relief.