For me it’s time signatures in music. I grew up playing instruments, played in several orchestras, etc. But no matter how many times someone tries to explain time signatures to me, it makes no sense. I don’t understand why people place such importance on it. To me, notes have a pitch and a duration, maybe some dynamics. That’s it. I don’t understand why people try to needlessly complicate it. It doesn’t give you anything.
My wife will hear a song and go “Oh neat, it’s in 5/8.” And I’m like “How tf do you know that, and why does it matter?”
Anything can be in 4/4 if you count hard enough.
That really bothered me at first! Kept thinking ‘why ever have a different time sig? No need for 13/8 (or whatever) when you can just sprinkle in double dotted 16th notes tied to 8th note (or whatever).’
Over time I slowly realized that it’s not about technically being able to write it, but rather describing what usually happens. (Tho I still don’t really understand, intuit, or hear any of it well.)