Dan Harmon is a great storyteller, but this system, and indeed all these "universal story structure" systems all either: 1) Are so generic they doesn't say any

Dan Harmon is a great storyteller, but this system, and indeed all these "universal story structure" systems all either: 1) Are so generic they doesn't say anything useful (like a horoscope which fit everybody). 2) Only matches some select stories. A good litmus test is if the system is compatible with Shakespeare's Hamlet. Given how populuar and well-regarded the play have been for centuries, we can safely say it is the system rather than the play which is at fault if the play does not fit the system. We immediately notice that Hamlet does not "Then return to their familiar situation", since he dies (along with most other characters). Also it is not really clear he have changed. Indeed, the genre of tragedy does not match the requirement to have the protagonist safely home in the end, so Romeo and Juliet is also out. These are not obscure examples, these are the most famous and well-regarded plays in the English language. TV-shows like Rick and Morty does tend to have the characters safely home in the end, so they can start in the "zone of comfort" in the next episode. On the other hand the characters rarely change. Even if they learn some lessons, they have usually forgotten them by start of the next episode. So I'm unsure if the system even matches Harmons own writing.