“City Slickers 2: The Legend of Curly’s Gold.” “Caddyshack 2.” “Ghostbusters 2.” “The Hangover 2.” “The Hangover 3.” The “Austin Powers” series. Why do so many comedy sequels fail so hard? What is it about comedies that makes franchises so stale and the films so bad? In theory, it should work, right? Affable actors, known characters, familiar situations; it could easily be more of the same as the first installment. But the problem is that comedy doesn’t work with “more of the same.” If you’ve known someone for a long time, you’ve probably heard a particular anecdote multiple times. The first time it was hilarious, the second time you knew what to expect, so the impact is inherently less humorous, and each subsequent time it loses some of its punch. The same can be said of comedy sequels. It’s not that they can’t succeed, but when they fail, it’s usually a matter of poor execution and lazy filmmaking that makes them so disappointing and terrible.

Let’s break it down a bit further. Most comedies are situation-based. True, there are funny characters reacting to the situation, but it is still a predicament of some sort that drives the story and the humor. “The Hangover,” for example, has a funny cast, but they are thrust into a comic milieu because of the situation of not remembering what happened the night before and piecing it all together while reacting to each new discovery with a signature personality. The problem in the sequels is that the novelty of the situation has already been squandered; we’ve already seen them have a problem with a lost night out, so why are we watching it again? Furthermore, it strains whatever credulity the plot already had by simply saying, “Here we go again.” What are the odds the same outrageous thing happens to the same people multiple times like that? If familiarity breeds contempt, then redundant and overwrought plots breed unhappy audiences.

Too few comedy sequels see the strengths in their characters, or else realize how paper-thin those characters were, and thus are hard-pressed to come up with a new situation in which these characters find themselves. Case in point: “Ghostbusters 2,” where the plot has been constructed by essentially pressing the reset button, returning the characters to where they were at the beginning of the first film. The Ghostbusters are no longer heroes or well-known figures, the idea of ghosts and apparitions are still a rarity that few people believe in, and there has to be another montage of the ragtag group coming together. Heck, even Sigourney Weaver’s character’s job is changed without much forethought. Rather than simply take off where the previous film ended, raising the stakes on new phantasms for the gang to take on or facing the responsibilities of being celebrities or something, it sticks to the reliable cookie cutter, simply regurgitating the same steps of the first film. Once again, Dana (Weaver) is under supernatural threat, and once more the city cheers on the group as they square off with their otherworldly foe. “Ghostbusters 2,” and so many other films, commit a cardinal creative sin and turn the novelty of the original into a formula to follow.

Even worse are the sequels that literally repeat jokes and situations from the original. The “Austin Powers” sequels devote whole scenes to rehashing the same jokes from the first film; “Horrible Bosses 2” revisits the same tropes of regular guys being in over their heads; and “Caddyshack 2” finds a new group to play out the snobs versus slobs battle, with boorish behavior coming up against the stuffed shirts, but this time with Jewish jokes! What was likely conceived as a nudge-nudge, wink-wink to the original falls flat. The punchline just can’t land the same way twice, and the diminishing returns take something fun and turn it toxic.

Of course, some comedy sequels have worked. “22 Jump Street” was able to succeed by becoming a metatextual comedy that tweaked the formulaic approach inherent in sequels. The “National Lampoon’s Vacation” sequels like “European Vacation” and “Christmas Vacation” take the same template of an idea (a wacky trip goes even more awry) but sails by on the inventive approach to new situations and expanding on the personalities previously established. In both cases, the filmmakers took the strong character work of the original and added novelty with a new situation or a new way of looking at those characters. The subtext of bromance in “21 Jump Street” is elevated to a literal rom-com level in its follow-up, which leads to new places to mine for jokes. As opposed to simply saying, “Here we go again” and shrugging, these sequels say, “Here we go somewhere else,” and it pays off greatly.

If doing the same thing repeatedly but expecting different results is the definition of insanity, then perhaps the definition of inanity is doing the same thing creatively and expecting the same impact. It simply isn’t going to happen when audiences already know the way things are going to go. Unless there’s something left to tell, something else to explore in that world that is actually novel to an audience, then perhaps it’s best not to repeat the joke or return to that comedy well at all. Nothing is worse than overstaying a welcome, squeezing all goodwill built up from the original with watered down clones that taint the memory of the core concept, all in the name of making a cheap buck with even cheaper jokes. If comedy is all about timing, then comedy sequels is an idea whose time has long since passed.