Anxious to develop drama hits, networks have started following the lead of successful skeins like “Law & Order” and “CSI,” which repeat well and don’t scare off viewers that have missed an episode — or eight.

Those individually wrapped shows more or less stick to the same formula week after week, serving as an easy entry point for viewers who don’t have the time to invest themselves in every episode.

On the flip side, webheads have mostly sworn off projects that revolve around ongoing plot lines and require more viewer devotion (think “Once and Again,” “24” and “NYPD Blue”).

In their race to eliminate serialized series, however, networks run the risk of turning off those passionate, loyal TV viewers who make a rigid appointment to catch their favorite shows.

“What makes a network stand out is the ability to produce shows that really galvanize us,” says TV Guide critic Matt Roush. “There’s value in being invested in characters and ongoing stories … I’m a fan of ‘CSI’ and ‘Law & Order,’ but you better have a pretty good formula.”

Indeed, shows like ABC’s recently departed “Once and Again” stir a response from viewers bordering on the fanatical.

(According to “Once” exec producer Marshall Herskovitz, one irate viewer even sent a burned-out TV set to Alphabet execs to protest its cancellation.)

That’s because auds of serialized dramas develop an emotional relationship with characters and their plights; for example, who won’t shed a tear when “ER’s” Dr. Mark Greene succumbs to a brain tumor at the end of the season?

But as viewers are inundated with more programming choices, those rabid fans have grown fewer in number. According to an oft-repeated statistic, even the most loyal viewers catch just two episodes a month of their favorite show.

And as critically acclaimed as they are, shows that require a large investment of time and feeling just don’t hold up as well in repeats these days. Skeins with a strong serial component are also an extremely tough sell in syndication and internationally.

“If I’m a business man, I want a program that repeats well,” says Jonathan Littman, who heads up “CSI” exec producer Jerry Bruckheimer’s TV arm. ” ‘CSI’ can be a much better business model.”

Hence the move toward development such as CBS’ Miami-based “CSI” spinoff; ABC’s “Flashpoint,” a drama set at the Centers for Disease Control; Fox’s “Fast Lane,” an actioner in the vein of “Starsky & Hutch”; and NBC’s “Rashomon”-style crime drama “Boomtown.”

All of those shows may contain some plot lines that carry over from week to week, but most of the action will commence and be resolved within the hour.

The move harkens back to TV’s earlier days. Stand-alone episodes — in which the suspense is resolved by the closing credits and characters end up exactly where they began — used to be the norm in primetime drama (“Dragnet,” “The Fugitive”).

Then came the 1980s, when serialized dramas such as “Dallas” and character-rich series like “Hill Street Blues” changed the way people watched hourlong programs.

As a result, webheads, anxious about losing viewers, were convinced that a serial element would at least keep ’em coming back. The payoff can be big during sweeps or finale time for shows with an ongoing storyline as well.

But then came “CSI,” coupled with “Law & Order’s” continued ratings dominance. So-called “procedural shows” are fast-paced, and stick to the facts ma’am, leaving less room for character development.

But that’s enabled a show like “L&O” to replace actors with ease — clearly, viewers are attracted to the show’s whodunit qualities, not its characters’ personal lives.

And it also allowed “L&O” to turn into a monster off-net hit on cable; after all, it doesn’t matter what episode from what season you’re watching, you know what you’re going to get.

That doesn’t attract a rabid “X-Files”-style fan base, but it does bring in a healthy variety of viewers each week.

“That white-hot passion may not be there (for ‘CSI’ and ‘Law & Order’), but I’d trade white hot passion for ratings consistency any day of the week,” says one net exec. “It’s just easier for people to get into those shows.”

Of course, “CSI” and “Law & Order” do it right. Without the crutch of ongoing dramatic storylines, newcomers will soon realize it’s not easy keeping the same basic concept fresh week after week.

“If there’s a glut of strictly procedural shows, then inevitably there will be a partial swing back the other way,” says Studios USA programming prexy Sarah Timberman.

There will always be a place for character-based drama, she adds. The trick will either be finding a way to merge that kind of storytelling with self-contained stories, or coming up with a low-budget serialized drama that’s viable in primetime.

“What the networks are opting for now is a higher number of less-engaged audience members,” warns Herskovitz. “That lack of passion may translate over time into a loss of viewers.”