There comes a time in every show’s life when it plateaus. No matter how good things get, it can no longer ascend, and the smart thing to do is to quit while it’s ahead. Financial considerations mean that no network — outside of the eminently classy programmers in the UK — will follow this rule. Networks love milking shows for all they’re worth. (Note the CW renewing Supernatural for a comical 12th season shows). Twelve is obviously preposterous, but how many seasons is the right amount? It might sound like the set-up for a joke, but a vampire show, a serial killer show, and the tits and dragons series all prove the Theory of Seven Seasons.
Lest you think the Theory of Seven Seasons uses an arbitrary number, let’s break it down. Buffy is a critically acclaimed cult classic that’s widely considered to be Joss Whedon’s best work (though some people disagree. The show lasted exactly seven seasons, the last of which introduced at least ten new (and pointless) characters who took screen time away from old favorites. It wasn’t a total waste of a season — it had its moments like “Storyteller” and “Conversations with Dead People,” but it’s unquestionably the show’s weakest.
Had there been an eighth season, the show would have likely ended on a downhill note. They made the smart movie, letting the series continue on in comic books.
Dexter too proves the Theory of Seven Seasons. The serial killer drama ended in a notoriously terrible fashion, and most former fans would tell newbie binge watchers to quit after Season 4. It didn’t get truly unwatchable until Season 8, for the simple reason that Season 7 was saved by the presence of Ray Stevenson.
Seven seasons. This is the golden number for long-running shows. Game of Thrones showrunners David Benioff and D.B. Weiss know it too. Although the show is now officially elapsing for at least eight seasons, their initial plan was no more than seven.
The Sopranos lasted six seasons, but as its sixth doubled down on the number of episodes; so it’s fair to call that seven. Five seasons is ideal — see The Wire, Six Feet Under, or the perfect finale of Angel — but if a show insists on running longer, it shouldn’t be by more than a season or two.