Season 1s are great, setup, some payoff, a bit of lead into the overarching story. Then season 2 to X. The heroes win and then lose in the final episode, cliffhanger to next season. People get bored. Final season is announced and they wrap up the show.
Hot take: Scrubs Season 8 was weak. Dr. Cox as chief was lame, the new interns were lame, the Janitor’s wedding was lame.
Season 9 was actually a bit of a dead cat bounce.