[Jun8]

Exactly, and you have to know when to let go, a la Seinfeld. Adventure Time handled this very well, I think: told what they had to tell and ended after that. Another canonical good example exiting at the right time is Calvin and Hobbes.

[lostgame]

Calvin and Hobbes also managed to avoid selling out. Bill Watterson was a genius for sure. Due to his actions, Calvin and Hobbes has retained it's wholesome charm, and as far as I can see, will for many years to come.