Before Nicktoons came about, Inspector Gadget was Nickelodeon's most-adored cartoon in the 80's. Clips of the show also appeared in some of Nick's promos. Looney Tunes on Nickelodeon was also treated this way.
The trope was averted for the very first Nicktoon to hit it big, The Ren & Stimpy Show. Because it came before this trope became prominent, it was only seen on Nickelodeon twice a week (on SNICK and on Sunday mornings). However, it was also run on MTV at the height of its success. Another likely reason it wasn't given marathon airings was the fact that they had so few episodes to run in the first place.
All That was the next big live action show for Nick after You Can't Do That On Television.
Rugrats was the first Nicktoon to really get this treatment. After the show was brought back from hiatus and saved from cancellation at the last minute due to the ratings for the reruns being high, the show was put back into production. Thus, it dominated most of the lineup and was running every day, at least four times a day (though in recent times, this is nothing, compared to how SpongeBob is treated). This led to Nickelodeon using Klasky-Csupo (the studio behind Rugrats) to produce at least six new shows for the network, including the RugratsSpin-OffAll Grown Up! which was born from another over-hyped special that got Nickelodeon's then-highest ratings ever at almost twelve million viewers. Meanwhile, all the other Nicktoons were basically ignored or cancelled outright. Though Rugrats was nowhere near as Adored by the Network back then as SpongeBob is now.
Back in the mid-to-late 90's, Garfield and Friends was adored more than any other syndicated show, airing twice a day and getting promoted often.
Sponge Bob Square Pants could be the posterchild for the trope. Since the show was uncancelled, it runs at least eight times on an average weekday. It will often be the first thing they show in the morning and the last thing they show at night, before turning into Nick At Nite, and it's the only show that they run at all different hours of the day to get pre-schoolers, after-school kids, and evening teenager audiences. "Special" SpongeBob episodes are hyped up and promoted more often than the regular Nicktoons on the network. Some days, it gets more airtime than all the other Nicktoons still on Nickelodeon combined. During 2009-2011, repeats get higher ratings than the average that most kids' shows nowadays have. Go on TV By The Numbers, look at the top cable ratings for the weeks and check out how many episodes will be there. However, ratings for the show have lately dropped, probably due to daily overexposure.
There was a three-day long marathon of nothing but SpongeBob in 2009 to promote the 10-year anniversary and the T or S special. Later during that week, even Nick At Nite aired a special about the production of the show.
On 7/18/10, an unannounced twelve hour marathon of SpongeBob plagued the channel, before an airing of Adventures In Babysitting.
On 7/29/10, of the 11 hours of Nickelodeon not including Nick At Nite and Nick Jr, nine hours were filled with SpongeBob and iCarly alone without any of their current Nicktoons showing and only two other shows aired.
During 2010, the Australian Nickelodeon had SpongeBob running from 12AM-6AM every night, for over a year.
A schedule change in April 2011 resulted in SpongeBob having over 60 airings that week.
The UK Nickelodeon had a 502 hour marathon of SpongeBob in Summer 2011 (that's two hours short of three solid weeks) for the Clash of the Bottom competition, where kids had to vote for their favourite main character. To top that off, it was the second-longest TV show marathon of all time, only being beaten by Boomerang UK's Scooby Summer.
On July 21, 2012 Nick aired a SpongeBob marathon to promote the "Super-Spongey Square Games", an hourlong block of new episodes devoted to sports. They also aired the 1-hour special "Truth or Square" and the movie.
Whenever a new episode is going to be aired (and a 15-minute one at that), Nickelodeon will hype it up with a big marathon and tons of promos that air on Nickelodeon, other Viacom networks, and networks that aren't owned by Viacom! note though the latter instance may depend on your cable/satellite provider, as some of them overwrite ads to air local commercials or promos for other networks That there just shows how much that Nickelodeon absolutely loves SpongeBob.
Hollywood news website Deadline reported that in January 2012, SpongeBob filled up about a quarter of Nickelodeon's schedule. As of October 2013, the Sponge now accounts for roughly 45% of the network's airtime!
Nowadays, it seems like SpongeBob is getting fewer and fewer airings. If it keeps up, the show may suffer the same fate as Who Wants to Be a Millionaire? suffered when ABC treated it the same way for many years.
iCarly spent several years as the adored live action show counter-part to Spongebob. Not surprisingly however, as it was the only show to even come close to matching Spongebob's ratings and popularity, up to and including an episode that broke the 12 million viewers mark. Like Spongebob it got the marathon treatment regularly.
Nickelodeon does this with any "big" Teen Com that has any form of success — Drake & Josh comes to mind fairly quickly and they even aired the Christmas special over and over even when it wasn't Christmas.
Speaking of Drake and Josh, they also liked playing the "Really Big Shrimp" special a lot. In the mid-2000's, it would air at least once a month.
Plus, when the network's teen-coms air new two-part specials, after their airing, it'll probably rerun lots of times shortly afterward. When "iStart a Fan War" premiered in mid-November, it aired a total of nine times in the remainder of the month alone. Similarly with "iParty with Victorious", because Nickelodeon went so far as to make an extended version of it.
Nick's love affair with iCarly is so over now. They have shown first-run episodes without any promotion at all and have been pushing Victorious instead.
After the premiere of Sam & Cat, the network repeatedly promoted reruns of the first episode, using the phrase "See how it all began" as if it hadn't aired just the day before. After two days of this the network dropped all pretenses and announced that it would air the first episode every single day that week.
Dora the Explorer used to be the most adored preschool show on Nickelodeon until 2013, airing at least four times during the morning hours.
As of July 2014, this honor now goes to Paw Patrol, running 4 episodes a day. Dora now only airs once a day.
Sometimes Nick combines overplayed shows into giant marathons or blocks that can take up entire days:
On 11/26/10, they played a six-hour SpongeBob marathon, followed by an iCarly marathon at 3, ending with iStart a Fan War at 7, and wrapped it up with the premiere of the Victorious special, "Freak the Freak Out".
On Latin America's channel, almost all weekends are 48 hour marathons of either SpongeBob or iCarly.
As of May 18, 2012, Nickelodeon can now be called "The Spongebob and Kung Fu Panda Legends Of Awesomeness Network". Why is this? Because Kung Fu Panda plays for 2 1/2 hours on weekdays, making it the second-most run show on Nick.
Fanboy and Chum Chum: Massive blocks on both Nickelodeon and Nicktoons, It seemed for a while that you couldn't go a single day of the week without seeing at least three episodes of it.
Often the same three episodes. Again and again and again. Seriously, for a while you could only see three to five episodes, total, of The Penguins of Madagascar and Fanboy and Chum Chum, even with the knowledge that other episodes probably existed. They would play them in hour blocks, yet you never seemed to catch a new episode.
T.U.F.F. Puppy has been getting adoration in the same way as Fanboy and Chum Chum, a new show that is being shoved down our throats, when SpongeBob has the day off.
Dragon Ball Z Kai is shown multiple times every day with flimsy excuses for marathons. It's 11/11/11? They promise to show 11 hours of the show. It runs at least 4 episodes a day.
Though the rights have expired and is no longer airing on Nicktoons. The show is moving to Adult Swim's Toonami block in Fall 2014
The block-series, Nick Studio 10, was crammed into the program during any possible rerun. It got so bad that Nick actually interrupted whatever show is playing to air a random clip of something and/or a Studio 10 skit instead of waiting for the next commercial break. An irrational Periphery Hatedom developed, and Studio 10 became a rare case of a series seemingly bullied off the air by social media.
Nickelodeon has been extensively advertising Sanjay And Craig. In fact, two or even three commercials for the show will air in a single commercial break. Commercials are even airing on different networks.
This event went so far as to advertise on Tumblr, leading to a backlash against the show because Tumblr ads were breaking into the users' dashboard.
Nick even loves to interrupt shows with Sanjay and Craig ads as well, playing a commercial right after a show's theme song. However, it's (thankfully) fitted so no content is missed.
Is today a holiday (Christmas, New Year's, Thanksgiving, etc.) or a special event on a different network such as the Super Bowl or the Grammys? Chances are that Rugrats in Paris: The Movie will be on tonight. The movie is also played every other week as well.
Before Rugrats in Paris, from 2009-2012, Nickeloden used these same excuses to air the first live-action Scooby-Doo movie.
Whenever there's a big SpongeBob marathon, you can almost always expect an airing of The Sponge Bob Square Pants Movie. Sometimes, they will air it TWO or more times in the same marathon. It was like this during the 10th anniversary marathon, as well as one promoting a new episode.
Nowadays it's gotten to the point where they'll play the SpongeBob movie just to fill space that they can't fill with more SpongeBob. No real rhyme or reason, you'll just tune in one day and there it'll be.
They also adored Jinxed back in November and December of 2013.
The second most run animated series on Nickelodeon is Rabbids Invasion. Expect to see at least 2 hours of it a day.
Back when TeenNick was still The N, when they first picked up One on One reruns in early 2006 they began running the show ad nauseam, with the occasional Degrassi re-run in the prime time slots and new episodes would air infrequently of their other shows. A year later in spring 2007, The N's line-up was two episodes of The Fresh Prince of Bel-Air, then two episodes of One on One, then two episodes of The Fresh Prince of Bel-Air, then two episodes of One on One. Degrassi completely disappeared from the schedule, save for re-runs at 3AM on the weekends.
Degrassi on TeenNick is an especially unusual case since Nick/Viacom does not own merchandising rights to the show, and Epitome Pictures makes separate agreements for DVD production.
Degrassi's also Adored By Much Music. When a new season starts, all day is given over to the runup to the premiere. This makes a little more sense for them - Degrassi and Epitome's other current production The LA Complex are Much's flagship original dramas.
Zoey 101 and Drake & Josh re-runs have more or less taken over TeenNick's entire schedule during the day and early evening. It's to the point that even long-time fans of both shows have expressed annoyance at the shows being played way too much in a given day.
Nick At Nite is every bit as bad with The George Lopez Show, probably worse. First, they would run marathons of the show for every occasion imaginable using any excuse they could get, no matter how shoddy. Then they did away with the excuses, and began showing marathons of George Lopez without even giving an excuse to do so. On multiple occasions, they aired over 40 hours of it in one week, setting up a bizarre situation — his self-titled Talk Show on TBS often competed with his own old sitcom.
It got so ridiculous that Nick at Nite decided to celebrate Saint Patrick's Day (which in America at least is viewed as basically being a day to celebrate Irish heritage) with "Luck of the Lopez" week.
The Nanny was also adored by Nick At Nite in 2010. Nick At Nite would play marathons of the show on major holidays, and aired three hours of it a day.
Nick At Nite loved Fresh Prince when they had the syndication rights to it. There were several times where they'd show four episodes in one two-hour block. It was also an "introductory" staple for a while, where it would be the first show after the regular Nick schedule ends, possibly to attract a younger crowd.
Part of what happens with Nick At Nite and TV Land is that when they get the rights to a new show, they always give it something of an introductory marathon to get people into the groove of watching it. They tend to do it with most shows when they first get the rights to them.