Yes, he didn't come up with the ideas from scratch as he was writing them. It took years to gain the experience and expertise. Yet he still saw the value in outlining when the time came to write it down.
> Filling out an outline like this produces an uninspired, boring, formulaic trash
So write a better outline. George R. R. Martin and Agatha Christie both used extensive notes and outlines as part of their writing process.
> She made endless notes in dozens of notebooks, jotting down erratic ideas and potential plots and characters as they came to her “I usually have about half a dozen (notebooks) on hand and I used to make notes in them of ideas that struck me, or about some poison or drug, or a clever little bit of swindling that I had read about in the paper”.
> She spent the majority of time with each book working out all the plot details and clues in her head or her notebooks before she actually started writing.
https://www.agathachristie.com/about-christie/how-christie-w...
I think the main confusion is about the speedrunning aspect. You don't speedrun gathering thoughts, you speedrun turning those thoughts (that took weeks, months, or years to develop) into writing. You may not struggle with writing, but a lot of people absolutely are.