They’re meant to reinforce one another.
I just had lunch with a friend, and we talked about how much fun it was learning the 5 different fretboard patterns of pentatonic (five-tone) scales on the guitar. When his practice was less developed, music theory had seemed boring and irrelevant to him, but now it was exciting and directly relevant.
It’s like this with just about anything you do, isn’t it? There is a theoretical side to just about everything you can do. Advanced mathematical formulae will help you do all kinds of science, but can seem irrelevant for the amateur lover of the natural world. The study of history will aid healthy analysis of political swings and round-a-bouts, but can seem tedious to the armchair politician. Etymology will help one choose the choicest words in your literary endeavors, but sound high-browed and lofty. Analytic philosophy will help one to interact with ideas more efficiently, but sound like a pedantic waste of time. Systematic theology will shape and enrich a life of worshipful obedience, but seem like detached speculation.