Good TV knows when to call it quits

Sometimes a great performance is all about knowing when to leave the stage.

With that in mind, I was actually pleased to read last week that one of my favorite TV series will end after its next season.

The producers of “Battlestar Galactica” announced last week that the show’s fourth season will be its last. In a statement on the Sci-Fi Channel’s Web site, producers Ronald Moore and David Eick said, “The show was always meant to have a beginning, a middle and, finally, an end. Over the course of the last year, the story and characters have been moving strongly toward that end, and we’re decided to listen to those internal voices and conclude the show on our own terms.”

As much as I’ll miss “Battlestar Galactica,” I agree that it’s time for the final act. Given the third season’s cliffhanger, I doubt Moore and Eick could squeeze out a fifth season.

The producers of ABC’s “Lost” had the same idea, and they plan to end “Lost” following its sixth season. Unfortunately, that means “Lost” has three seasons left before the curtain drops, which is probably too long to drag out the story. But at least the next three seasons will be only 16 episodes each, rather than the standard 22 to 26 of U.S. network television.

The idea that TV shows should have thought-out beginnings, middles and endings — like movies or novels — is relatively new, at least in the U.S. But some have tried it before, with mixed results. Producer/creator J. Michael Straczynski conceived his sci-fi series “Babylon 5” as a five-year-long “novel” for television. But the constant treat of cancellation led to Straczynski rushing to wrap things up during the fourth season. Then, when the fifth season received the go-ahead, he was forced to pad about half of it with filler. A couple of ill-conceived spin-offs didn’t help, either.

Obviously, not every TV show lends itself to the beginning-middle-end format. Episodic shows (police and legal dramas, soap operas and comedies) can go on forever. Each episode is either a self-contained story or a jumble of overlapping plots so that when one plays out there are always half a dozen others to follow.

Episodic television is great so long as the show’s creators can keep things interesting. After seven seasons, I’m still hooked on the original “CSI.” And with a few unavoidable ups and downs, the original “Doctor Who” sped along for 26 seasons, until a shortsighted BBC bureaucrat killed it just as it was on a creative upswing. Now a revived “Doctor Who,” currently at three seasons and counting, has picked up where the original left off.

But how many shows overstay their welcome, phoning it in well past their prime? While some networks strangle new shows in their cribs (I’m looking at you, Fox), NBC seems intent on keeping its flagging franchises on life support. Remember when “ER” was must-see TV? Yeah, me neither.

NBC is also taking heroic measures with its three “Law & Order” series, the youngest of which just wrapped up its sixth year. The network is loaning out “Law & Order: Criminal Intent” to its corporate cousin, USA. Meanwhile, the original “Law & Order” is about to enter its 18th season of “ripped from the headlines” plots.

As someone who used to be addicted to “Law & Order” marathons on TNT, I can now say I just don’t care anymore.

Not every TV show should follow the beginning-middle-end path “Battlestar Galactica” and “Lost” are paving. But certainly they all can learn from the example of knowing when it’s time to stop.