When HBO aired the long-awaited Deadwood movie on May 31st, nearly 13 years after the network unceremoniously canceled the series, it was the culmination of a long journey. The most dogged fans had spent a decade pestering HBO executives and Deadwood cast members to return to their fiercely beloved but sparsely watched adult Western, and give it a proper finale. A lot of people were waiting for this moment, hoping the movie would be as great as the original.

And while they were spared a crushing disappointment, the first half of 2019 has still been bittersweet for nostalgic TV-watchers. After Fox canceled the dearly beloved but low-rated sitcom Brooklyn Nine-Nine last year, NBC picked it up, and starting in January 2019, the network started airing new episodes that are every bit as heartfelt and funny as the show’s best. That’s great news for anyone who’s ever fired off an indignant tweet after a quality TV series was killed.

On the flip side, in mid-March, Netflix finally got around to airing the second half of Arrested Development’s fifth season, and that once-groundbreaking comedy doesn’t look so good anymore. An excellent new take on Project Runway arrived on Bravo in March, followed by Jordan Peele’s hit-and-miss Twilight Zone revival in April, and a new update on Armistead Maupin’s Tales of the City in June. Later this year, we can look forward to revisiting Veronica Mars, Blue’s Clues, Are You Afraid of the Dark?, and many more familiar series that have been reimagined and updated.

For telephiles, hope springs eternal. Years of successful grassroots campaigns have convinced fervent fan bases that if they’re passionate and loud enough, they can resurrect the dead. In March, social media exploded with outrage over Netflix’s cancellation of One Day at a Time, with the show’s creators and their followers clamoring for someone — anyone — to step in and “#saveODAAT.” (Which the Pop network did, hours after this article was first published.) In May, more than a million fans signed a petition to remake the final season of Game of Thrones with different writers. Nobody is eager to say goodbye to their TV friends, and the success of fan campaigns to bring back shows like Futurama have emboldened fans to the point where they expect to be heard — especially when the people behind a canceled series are also actively pushing to continue their planned story.

But while revivals and reboots tend to arrive with a lot of joyous fanfare, not all of them are ultimately successful, either commercially or creatively. They fail for a variety of reasons: sometimes so much time has gone by since the show’s original era that its dynamic or characters seem quaint and out of place. Sometimes the creators have different agendas than the fans. Sometimes a show like Arrested Development returns, and the alchemy that made it work in the first place just isn’t there anymore, and everything feels… off.

But sometimes, everything falls into place, just as fans hoped — or at least enough into place that they don’t feel cheated. Which is why fans keep pushing, even though they so rarely get exactly what they want. Here are a few of the common pros and cons of bringing back a canceled series.

PRO: It’s great to see familiar characters again.

For fans of a given show, this is often the main reason to root for a revival, whether it’s a direct continuation, a spinoff sequel, or a reunion movie. Gilmore Girls fans are eager to catch up with Lorelai and Rory. X-Files obsessives are excited to see Mulder and Scully again. Futurama lovers are happy to see more of Leela and Fry.

Television networks and writer / producers have fed off this nostalgic warmth for decades. Back in the late 20th century, they used to exploit it in more roundabout ways — most often via retrospective specials and TV movies, where characters like Perry Mason or the Brady family returned to action for a night. Sometimes when these one-offs did well enough, they led to more. NBC kept running new Perry Mason movies throughout the late 1980s and early 1990s, until star Raymond Burr died. Between 1989 and 2003, ABC aired new Columbo movies, some of which were as good as the classic 1970s episodes.

TV creators have also kept fans’ favorite characters alive through spinoffs like Frasier, which carried on strong for a decade after Cheers. Two of the best dramas on television today are, ostensibly, revivals via spinoff. The Breaking Bad prequel Better Call Saul and The Good Wife sequel The Good Fight only share a few key characters with their parent shows, but tell the same kinds of stories with similar themes. Audiences who followed the originals closely are delighted to have them around.

CON: Sometimes it’s hard to see the actors the same way.

Arrested Development writer / producer Mitchell Hurwitz made a lot of mistakes with the Netflix version of his show, but one of the biggest issues was beyond his control. Some of his core cast-members, including Jason Bateman, Will Arnett, Tony Hale, and Michael Cera, built thriving careers off the foundation of their Arrested Development work. That makes it harder to see their faces and hear their voices now without thinking of all the similar characters they’ve played since, from Bateman’s self-absorbed dorks in movies like Game Night to Hale’s nebbish assistant on Veep.

And then there’s the case of Jeffrey Tambor who, between the cancellation of Arrested Development and its Netflix return, took on what looked like it was going to be his career-defining part as Maura in the award-winning Amazon dramedy Transparent. But just before Arrested Development came back, Tambor was fired from Transparent over issues of sexual harassment and general boorishness. The behind-the-scenes information made it harder to enjoy Tambor’s work, for the same reasons that Roseanne Barr’s incendiary, racist Twitter activity soured her Roseanne comeback in 2018.

PRO: Revivals can update the old shows’ content to reflect modern times.

British television tends to handle the revival conundrum well by keeping TV series’ individual seasons short and self-contained, and by only producing new ones when inspiration strikes. It’s not uncommon in the UK for years to pass between seasons, and for the later iterations to take advantage of this time off, by updating the material to reflect a changing world. Steve Coogan’s various Alan Partridge shows over the course of nearly 30 years are a good case in point. His pompous broadcaster character remains a twit throughout each new installment, but Partridge’s career is a bit different each time, depending on whether his brand of windbaggery is in fashion in the real world.

The teams behind Twin Peaks and The X-Files took different approaches to updating their respective universes. David Lynch introduced more modern technology to the retro world of Twin Peaks, then just kept on going, tilting into the realm of science fiction with his super-advanced crime-labs and stealth communication devices. He and Mark Frost made little effort to reflect current reality accurately for their 2017 revival of the show, but they did make sure to distinguish the 2010s from the 1990s, when the original show first aired. The X-Files writers, meanwhile, included episodes in the most recent season that dealt with the likes of AI, algorithms, and “fake news” in ways that were frighteningly of-the-moment.

CON: Sometimes those changes inadvertently lose something special.

One concession to modernity both The X-Files and Twin Peaks made was to use the latest cameras and lighting rigs, which in both cases gave the shows a visual style markedly different from the way they appeared on TV in the 1990s. Their daytime images looked brighter and flatter; their nighttime images looked darker and sparer. Neither show suffered dramatically from the changes, but it did take some adjustment to get used to the new look.

The same was true of the Firefly movie, Serenity, which made the world of that show look more expensive and cinematic, to some extent working against the ramshackle charm of the TV version. Netflix’s revival of Gilmore Girls disappointed some fans with its movie-like narrative structure, and its frequent trips outside of the enchanting tourist town of Stars Hollow. CBS All Access’ The Twilight Zone reboot is taking a more TV-MA approach to Rod Serling’s original, which sometimes makes the science-fiction / horror anthology feel newly relevant, but at times just makes it seem more vulgar.

Even with the old Perry Mason TV movies, the look of those new episodes (shot in color instead of in black and white, and set mostly in Colorado instead of Los Angeles), and the changes in tone (with storylines often a little racier or more violent than the original) makes those later adventures more of a curiosity than a must-see.

PRO: They make fans happy!

The ABC sitcom Cougar Town never became a sensation during its three years on network TV, and after it moved to TBS for three more seasons, its viewership dropped to around 2 million per episode. But those 2 million were thrilled that one of the most amiable, light-hearted hangout comedies of its era had stuck around for a few extra years. It was like a little unexpected gift, every week that Cougar Town’s cast of goofy Floridians was still on the air.

This is the way it’s supposed to work whenever fans push for a canceled show to come back. When the people who make the series are as excited and inspired as their viewers, it’s hard for either side to complain about getting more of a good thing. See also: the latest version of Mystery Science Theater 3000, or the Veronica Mars movie, both of which happened in large part due to fans contributing to crowdfunding campaigns.

CON: Fans don’t always agree on what they want.

On the other hand, not every MST3K buff is totally on board with the new Netflix version of the show, which features a different host and a tweaked concept. A number of Veronica Mars fans were let down by the movie, disagreeing with how the heroine’s life and relationships had changed since her college years. The eccentric sitcom Community had a strong final season after it moved to the streaming service Yahoo! Screen, but not enough of the people who watched the series religiously on NBC followed it to its new home — in part because of the obscurity of the platform, and in part because not all of the original cast made the transition.

The immediate rush of seeing old favorites from The Mindy Project or Gilmore Girls back on the big screen often gives way to a return of all of the old online arguments about what these characters should be doing and who they should be dating. Sometimes it might be better just to let the fan-fic crowd keep telling the version of the story that’s in their heads, rather than disappointing them by going in a different direction.

PRO: Some of these shows were canceled before their time.

Some of the most successful revivals — from a creative perspective, that is — have been the ones where production barely skipped a beat. Taxi moved seamlessly from ABC to NBC for its final season in 1982. Buffy the Vampire Slayer shifted from The WB to UPN for its last two years. Supergirl jumped from CBS to The CW immediately after its last season. Brooklyn Nine-Nine slid right over from Fox to NBC this year.

Not much was lost in any of those cases. Supergirl had to move its production from California to Canada, and say goodbye to Calista Flockhart, whose contract stipulated that she had to be based in Los Angeles. But for the most part, a machine that was already rolling along just kept chugging.

And in April, in a story about TV’s most powerful producers, The Hollywood Reporter mentioned that This Is Us creator Dan Fogelman may use his newfound clout to revive his acclaimed baseball drama Pitch, canceled in 2017 after one short season. When a series has that kind of talented creative team, and devoted fans (no matter how few in number), it’s heartbreaking to see it yanked off the air due to network balance sheets not lining up. Even from a business point of view, there are reasons to eke out a few more seasons of a show on a new network. How much more money have the people who own pieces of Buffy, Taxi, Supergirl, and Brooklyn Nine-Nine earned over the years thanks to having more episodes to sell?

CON: There’s something to be said for quitting while you’re ahead.

The CW’s Crazy Ex-Girlfriend ended this spring, and Jane the Virgin will wrap up in July. In both cases, their creators decided it was time to wrap them up, though the fact that neither show was ever a massive hit may have been a factor. And that’s okay! As much as fans of both shows might want them to keep running indefinitely, it’s good that both can finish their runs on terms that satisfy their networks and their producers. That’s pretty rare for the TV business.

Even shows pulled after one or two seasons of dire ratings may sometimes be better off as monuments to their own potential. Pushing Daisies, Better Off Ted, Happy Endings, Great News, The Middleman, even Firefly (movie notwithstanding)… These series never had a chance to let their devotees down, because they were yanked off the air while they were still great.

This doesn’t mean that people who dearly missed Deadwood shouldn’t have pushed for the movie, or shouldn’t be grateful that they finally got it. But just imagine how revered Arrested Development would still be if Netflix had never “saved” it. Maybe some wishes weren’t meant to come true.