Yeah, that's another thing. I've tended to feel that serial fiction of pretty much any sort probably has a limit of somewhere between 50 and 100 episodes at the upper limit. Most non-superhero comic series I've liked have played out their story over that span (Sandman, Y: The Last Man, Transmetropolitan, etc...) and any TV series I've really gone for has probably had about that limit, too. Even the latter Star Trek series, as much as I like them, probably could have cut down about 70-100 episodes from their entire runs and not lost anything.