NCIS has been part of the television landscape for the past two decades.

Following a two-episode backdoor pilot on JAG in 2003, the redundantly named Navy NCIS: Naval Criminal Investigative Service debuted in the fall of that year.

Although it started slowly ratings-wise in its first couple of seasons, a franchise soon was born.

Now in its 21st season, NCIS has produced more than 450 episodes and six spinoff series, a record unmatched in TV history (although Law & Order fans doubtless will quibble).

Maybe now, shortly after the series said goodbye to its second-most popular character on NCIS Season 21 Episode 2, would be a good time for a hiatus.

That's insane, you say, what with two new spinoffs in the pipeline.

Look back fondly

Let's start with the fact that every day, on cable and streaming, fans can watch their favorite episodes from the golden years of NCIS, back before Abby, Tony, Ziva, Ducky, and especially Gibbs all departed.

That's not to denigrate the current cast. I'll watch anything with Gary Cole, going back to Midnight Caller.

The simple fact is that viewers just tire of long-running programs. They're bound to compare new episodes to ones that came before and judge through rose-colored glasses of nostalgia.

As a case study, consider CSI: Crime Scene Investigation, which burst onto the scene in 2000.

Suddenly, forensics became a popular course to study while viewers discovered The Who through the series theme song.

CSI's success spawned spinoffs CSI: Miami (2002) and CSI: NY (2004). Both enjoyed respectable runs, with the former lasting a decade and the latter going nine seasons.

The flagship went out in 2015, with CSI: Cyber, one last attempt to remain relevant, airing for two seasons after that.

So what kept CSI from reaching the lofty episode numbers of NCIS, Law & Order: SVU, and ER?

Cast instability, from which CSI and its spinoffs suffered, never helps. But the above-mentioned, longer-running shows all dealt with that.

Viewers might have stopped caring about whether our heroes could solve their case by finding that one crucial piece of detritus.

In short, been there, done that.

CSI was reincarnated in 2021 as CSI: Vegas, a hybrid featuring a whole new team with O.G. characters dropping in to visit and show the new kids how it's done. The contemporary criminologists also teach those old dogs some new tricks.

Yes, it's a transparent attempt to draw the old viewers into the new show. But that hiatus also allowed for expectations to be lowered. It's just great to have it back, in whatever form.

NCIS could soon be experiencing that same "been there done that" situation.

Spinoff success varies

NCIS: Los Angeles lasted a robust 14 seasons but faded narratively by the end after Linda Hunt's role as Hetty Lange got cut back because of the pandemic.

But, despite a colorful backdrop, NCIS: New Orleans survived only seven seasons, plagued in part by frequent cast changes.

Hawaii has always been a friendly place for TV series (Hello, Hawaii Five-0 and Magnum P.I.). But NCIS: Hawaii has been a slow starter over three seasons, partly due to a lack of star power.

Enter LL Cool J's Sam Hanna, consistently among the best characters on NCIS: Los Angeles, who is joining NCIS: Hawaii for an unspecified number of episodes. Sure, it's an apparent effort to bring in his old show's fans seeking a new procedural. But it is better already for his presence.

NCIS: Sydney arrived with much fanfare to Paramount+ last November. However, despite the beautiful Australian scenery, the series itself is, how to put it, derivative.

There was the gruff leader resistant to authority (Mackey/Gibbs), the wily medical examiner (Doc Roy/Ducky), the hunky lieutenant (J.D./Tony), the eccentric lab tech (Blue/Abby), and the probie (D/McGee). You get the picture.

Perhaps based on how the last three spinoffs have performed, the two future spinoffs will mine the mothership instead of traveling to another city or country.

To be narrated by Mark Harmon, NCIS: Origins (that beats Young Jethro) will focus on the start of Jethro Gibbs' NCIS career and is set to air in the 2024-2025 broadcast season.

Reaching back

Austin Stowell will play young Gibbs. No explanation has been given why Harmon's son Sean, who played a younger Gibbs seven times during the series, wasn't chosen for the role other than his status as a producer on the show. But he would have been a natural choice.

This should present an excellent opportunity to show younger versions of NCIS characters, at least those old enough to reach back that far.

The crucial question is, after all that's been revealed about Gibbs over the run of the series, what stories remain to be told?

Then there's the unnamed reunion of Tony DiNozzo and Ziva David on Paramount+ (The Tiva Power Hour?)

Yes, Gibbs' prodigal children will be reunited for the first time in a decade. Perhaps Michael Wetherley and Cote de Pablo discovered the grass isn't always greener.

The premise for the series is that after Tony's security company gets attacked, he and Ziva go on the run with their daughter Tali across Europe. That will undoubtedly require a streaming budget.

This was a project that was going to happen.

Fans want to be caught up on Tony and Ziva's story, even though they've continued to pop up on NCIS since their departures. And Paramount wants those broadcast viewers to switch to streaming.

But, again, how much story is there still to be told? And can they recapture their chemistry while being parents fleeing with their daughter?

Too much at once?

So, it's conceivable that five NCIS programs could be airing sometime in the 2024-2025 season (if that term still holds any validity).

Although much overlap is unlikely, how much NCIS is too much? And how much are consumers willing to pay for that programming? Or might they just walk away?

Maybe some of those five series, especially the flagship, should take a lengthy break that isn't a result of strikes or pandemics.

Viewers might appreciate what they no longer have rather than being bored by abundance.

Joni Mitchell put it best: "Don't it always seem to go that you don't know what you got 'til it's gone?"

That could well be the case with NCIS.

Dale McGarrigle is a staff writer for TV Fanatic. Follow him on X.