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?”
It could be ADHD. It could also be anxiety disorder. I was a history major in college, so I had a ton of papers to write. My anxiety made if extremely difficult to write anything. Like you, I’d write it out, delete, rewrite, delete etc. It was awful. At the time, I would actually start drinking to the point of being slightly inebriated. I found I could actually write better at that point, because the alcohol shut down that anxiety (and if I am honest, it made me give less of a fuck about what my professors would think of my writing). Obviously, not a great solution, but it was good short term and I always got good grades on my papers. Now that I am better medicated for my anxiety, I imagine it wouldn’t be so bad to write a paper now. Trouble is, my job really doesn’t require me to write much lol.