Professional writer here. On our longer work, we go through multiple iterations, with lots of teardowns and recalibrations based on feedback from early, private readers, professional editors, pop culture -- and who knows. You won't find very clear explanations of how this happens, even in writers' attempts to explain their craft. We don't systematize it, and unless we keep detailed in-process logs (doubtful), we can't even reconstruct it.

It's certainly possible to mimic many aspects of a notable writer's published style. ("Bad Hemingway" contests have been a jokey delight for decades.) But on the sliding scale of ingenious-to-obnoxious uses for AI, this Grammarly/Superhuman idea feels uniquely misguided.