Our resident critic muses on what defines a successful TV series

For an American TV series, success has long been defined as 100 or more episodes. The creators of a series — usually not the networks — start making big money when they collect enough episodes to sell as syndicated reruns on local stations (oh, boy, Growing Pains every day of the week!). But the business has changed. There are now more places to sell old shows: to foreign networks, to videocassette customers, and to cable networks. So the time has come to change the rules, to give us more shows like Frank’s Place and fewer that are kept alive just to feed coffers and egos. We need to create a new definition of success; the old one is not serving us well.

A few successful series can go on forever. Cheers is still great, long after others would have gone stale. Some series are too successful and live too long. The Cosby Show is headed for a seventh season, but four seasons were more than enough for that old bonbon. Newhart is going off the air about one season too late; the stories were getting ridiculously stretched, what with Michael’s breakdown and all. Kate & Allie and Cagney & Lacey lasted a little too long and turned twinkie. All in the Family and Archie Bunker’s Place set new records for overstayed welcomes. They were all spectacular shows. The only thing wrong with them was that they stayed until they finally were forced to leave.

M*A*S*H and The Mary Tyler Moore Show, on the other hand, were hits that knew when to say good-bye. Miami Vice and Moonlighting also knew when to fade to black — and even though they did so before reaching the longevity of a killer hit, they still manage to find life after death on cable and on video-store shelves. I’m glad for that. The only thing that made those shows ”failures” was that they didn’t last as long as Cosby. That’s not failure at all.

Of course, many good shows die too soon. All Is Forgiven, starring Carol Kane and Bess Armstrong, was wonderful but wasn’t given a chance. Ditto Frank’s Place. Lots of people think Beauty and the Beast should still be alive. And I fondly remember the short-lived Duck Factory; I’m probably the only person not on its payroll who does.

And then there are shows, moderately successful shows, that are forced to live too long — for the audience or for the creators — so they can try for that 100-episode jackpot. The Wonder Years was genius — but then the geniuses behind the series left, and yet the show goes on, weaker without its creators. As much as I admire China Beach, I’m not sure I want to keep watching it for five years; maybe it’s not quite as good or maybe I’m just losing interest. I’m not suggesting that either series should be killed. But if they did die now, I’d remember them fondly. I’d consider each a raging success. I’ll bet that Twin Peaks will turn out to be a show like these.

What American TV needs is a few slots for limited-term series — not miniseries with beginnings and ends to their stories but regular series with limited lives, shows that don’t have to stretch themselves thin. Britain has sent us some delightful short series: The Good Neighbors, imported here on PBS, and Solo, on A&E, went on just long enough.

A few limited-term series on American TV could draw fresh talent — especially the really good and really busy producers, writers, directors, and stars who stay away from series TV because they don’t want to be trapped for half a decade. Such series would give us TV filled with good ideas and with variety. But for this to happen, some other rules will need to change: For instance, networks aren’t allowed to own many of their shows, but perhaps they should be, so they could share in the riches and the risk of making them. And we in the audience would need to change our habits and expectations, enjoying shows — like flowers and summertime days and bags of potato chips — while they last.