Commentary : KNOWING WHEN, AND WHERE, TO PULL THE NETWORK PLUG

On Dec. 2, CBS introduced “Second Chances,” a prime-time, romantic mystery series from the makers of “Homefront.”

But for their sake, let’s hope the producers know that when it comes to new shows with low ratings, there have been precious few second chances on CBS this season.

Granted, the No. 1 network was probably just cutting its losses and doing the public a favor when it canceled Glenn Frey and “South of Sunset” after just one broadcast. No great outcry was heard, either, when “It Had to Be You”--a supposedly romantic comedy starring Faye Dunaway and Robert Urich--met its inevitable demise. And, in fact, congratulations and celebration may have been in order when CBS canceled “The Trouble With Larry,” perhaps the most obnoxious sitcom ever made, which starred Bronson Pinchot.

But did the network pull the plug too early on “Angel Falls,” a prime-time soap featuring Peggy Lipton and James Brolin?

Here, after all, was a show that, to begin with, was catering to the same kind of audience “Second Chances” will be looking for and, perhaps more important, could have been riding the wave of trashy popularity that “Melrose Place” is now enjoying.

ABC, NBC and Fox, by comparison, have shown remarkable restraint.

NBC has yet to cancel a new show as of this press time, though fans of “Against the Grain” should probably prepare themselves for bad news.

Fox Broadcasting, for all practical purposes, has given Robert Townsend and his “Townsend Television” the gate. The highly offensive “Daddy Dearest,” with Richard Lewis and Don Rickles is, happily for good taste, that close to a similar fate.

It’s indeed a shame, however, that one of this season’s most unusual, if imperfect, experiments--ABC’s “The Paula Poundstone Show”--was yanked after only two broadcasts (only the first was seen in Southern California).

Talk about comedy-variety, a show that was different. Did you catch: Sam Donaldson’s politically oriented read of “Where the Wild Things Are”; Poundstone’s interview with a bunch of economists spinning around on an amusement park teacup ride; or the show’s theme song (“So you’re home on a Saturday night. Don’t you have a social life?”)? Unfortunately, the ratings don’t get much lower than Poundstone’s (even on Fox Broadcasting).

Of course, ratings, as even the most casual industry observer knows, aren’t everything.

That’s why CBS’ “Picket Fences” is still on the air. In addition to a sweep of the drama category at this year’s Emmys, the hourlong drama has big critical support and friends in high places (namely, CBS Entertainment President Jeff Sagansky).

Not that it’s likely to stay there beyond this season if, despite CBS’ high-profile promotional efforts, “Picket Fences” continues to perform at sub-10 rating levels. (As someone at CBS said, “We don’t do 10s.”)

Considered at risk at ABC is “Joe’s Life” and “Moon Over Miami,” as well as “George,” which already has undergone reconstructive surgery behind the scenes this season and has had a bad show-business buzz (including false reports of cancellation) from the start.

But whatever a network does to make a show work, eventually it needs an audience (just ask Tom Arnold if you don’t believe it). What programs have not had in recent years is time.

But with the exception of CBS, which may be trying too desperately to hold on to its No. 1 status, it would appear that the Big Four are adopting a renewed attitude of patience.

That’s why bottom-dweller “Bakersfield, P.D.” on Fox, one of this season’s funniest shows, is expected to stay on the air at least for the rest of the season and why such ratings sleepers as ABC’s “Lois & Clark: The New Adventures of Superman” could turn out to be the next “Cheers” or “Hill Street Blues”--shows that began with miserable ratings.

Who knows? If the networks start showing some patience, maybe viewers will take their fingers off the remote control.