I get where you’re coming from, but how about forcing authors to finish books before abandoning them (e.g. Game of Thrones) or dying before they finish them (Wheel of Time). See where I’m going with this? ;)

The problem is, some shows have planned outcomes. Babylon 5 was a sci-fi show in the 1990s (Star Trek Deep Space Nine was actually loosely based on it, though that may be anachronistic to members of the current generation — not saying you are) that had a planned four seasons. They wanted another one, so they had to shoehorn some stuff in to make it work.

Supernatural is a much better and more recent example. It was planned for five seasons, but it was pushed out to, what, seventeen seasons? Something ridiculous like that. The show was printing money and the cast and crew were willing to work on it, so they kept churning them out.

Game of Thrones, like Fullmetal Alchemist and Tokyo Ghoul in Japan, had their shows catch up to their source material, so the show was forced to write their own ending. With Game of Thrones, the author walked away from the series (but he is writing spinoffs). With Fullmetal Alchemist, the author finished the series, and a second anime series was commissioned that started with an anime original episode, summed up what the first series got right in 9 episodes (covering something like 25 episodes!), and then finishing out what the author wrote. Tokyo Ghoul’s second season was completely made up, and did things the books (which weren’t written at the time) didn’t do, like kill off a major character. So while they did wait for the series to finish before continuing, they didn’t explain when that character came back in season 3. Oops. Conversely, and I think much worse, The Promised Neverland ended before its second season came out, but instead of doing five or six seasons like they could have, they just crammed all that extra content into one season. There are episodes where crew members have demanded their name not be attached to it — some have no writing or directorial credit!