I don't get annoyed by the repetition, I actually enjoy it when it's interesting sounding words or the way a sentence was said was funny wo me when I first heard it. Conjugational recombination is a great word, btw!
The only theory I have is that it might be a form of echolalia, where instead of repeating words out loud you just do it in your head (maybe something like supressed echolalia? I've heard some people online say that it can present that way, but idk how generally accepted that idea is.) As far as I know echolalia is also a symptom of tourettes. I don't know if it can also occurs in allistic people.
Definitely read The Anatomy of Story if you're a writer/interested in writing as a craft. It is by far the best guide on plot structure I have ever read and even though it focuses mainly on Hollywood plots it can be adapted to any story form. I use it as a starting point for everything I write, highly recommend it!