I was thinking maybe understanding key signatures, but I think you can probably write a chord patte
rn/melody without fully understanding what key you're in or that this chord is the IV or that chord is the vii or whatever..
i'd personally like to ditch the roman numerals. they're just numbers, and i think the roman is much harder to read. i prefer arabic numberals instead (1, 2, 3, 4). also sometimes called "nashville numbers"