Why is it good news that one of my favorite shows has announced that it's going off the air? Because it isn't going off the air till 2010, there will be three more (16-episode) seasons and they'll run re-run free, and if there was ever a show whose creators needed an end-date to shoot for, it's Lost. But there's a larger lesson here, and one that I wish some other great TV shows had taken to heart: Imagine how much better The Sopranos would be if David Chase had been kept to four or five seasons, or The X-Files if Chris Carter had stopped churning out episodes in 1998 or so. I know Deadwood fans were sorry to see David Milch's revisionist Western cut off after three seasons, but maybe they should consider themselves lucky that there will never be a season four, or seven, or twelve (Al Swearengen faces off against William Jennings Bryan for control of the Populist Party! Hijinks ensue!). The same goes for The Wire, which seems poised to leave on a high note after this year's final season with its "best show on TV" halo still untarnished.

As a general rule of thumb, I think the better the show, the more it needs a cut-off date. Three's Company could have run forever; Seinfeld should have ended a season or two earlier than it did. Ditto the long-running Beverly Hills 90210 versus its far superior heir, The O.C., which could have left on a George Costanza-style high note by calling it quits after its near-perfect first season. Similarly, I'd think more fondly of HBO's Rome if it had only been a mini-series, without the mediocre second season, and I'm worried there's a similar sophomore drop-off awaiting Big Love. Leaving too soon makes a show immortal, while leaving too late ... well, would My So-Called Life be remembered as fondly as it is if we'd had to watch Angela Davis and Jordan Catalano get together, break up, get back together, break up - and then, worst of all, go off to the same college?

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