I like it when I think of it as another American Horror Story season. It's a bit too convoluted for me to think of it as a reasonable prequel. Sarah Paulson is being way too Sarah Paulson, which is great as a standalone thing, but not enough how I would envision Ratched in her youth. The connection between the two is to me very thin, almost nonexistent minus borrowing some of Ratched's backstory, and embellishing it a little too much. Almost like it was a pretext for making an original story about a nurse slowly descending into sociopathy and still getting an audience by riding on another movie's coattails.
Still very entertaining.