To be continued ... Many TV serials have already left us with cliffhangers

Last fall, network executives were all but declaring this the TV Season of the Serial — in addition to the slew of shows with storylines that continue from week to week returning to their schedules, executives at ABC, CBS, NBC, Fox and The CW added a whopping 19 more.

By midseason, some critics were declaring the effort a big flop and predicting the end of serialized shows on network TV.

It's become a bit of a joke. The CW's chief publicist, Paul McGuire, welcomed critics to the January press tour by saying, "We look forward to making today an interesting and fast-paced one. And if it isn't, well, I blame the serialized drama."

As with all things in TV, this is cyclical.

"It's so funny. Just last year we talked about, 'Are you going to put more crime dramas on? We've had enough with the crime dramas!"' said CBS Entertainment president Nina Tassler. "Now ... it's like, 'Oh, my (gosh), it's enough with the serialized dramas!"'

If the executives were wrong last fall, so were those critics at midseason. The truth lies somewhere in the middle.

Of those 19 new serials, four — "Brothers & Sisters," "Heroes," "Men in Trees" and "Ugly Betty" — have already been renewed for next season.

A 21 percent success rate is just about what the overall success rate is for all new network TV shows. If one or two more get picked up — certainly a possibility — this year's crop of serialized newcomers will exceed that average.

Part of the thinking among network programmers is that serials are a risk, but they offer a big reward. If they prove popular with the viewing public, those viewers will come back week after week. Networks have done studies that indicate even people who identify themselves as fans of a particular show see fewer than half of the first-run episodes in a season.

"Serialization is still one of the biggest hooks that we have into an audience," NBC Entertainment president Kevin Reilly said. "I think it's potential rocket fuel when you hit it."

The risk comes because you're asking viewers to tune in to every single episode. "The show requires a very intense and ongoing commitment," said "Lost" executive producer Damon Lindelof.

The risk increases when there are so many serials on the air, because viewers can't commit to all of them.