The summer movie season, with its flood of sequels, remakes, and reboots, always gambles big on nostalgia. And Summer 2015 seems to be more dependent than most on good will and fond memories of past hits.



Of course, the gamble doesn't always pay off, as this weekend's box office results made clear.



"Mission: Impossible: Rogue Nation," the fifth film in Tom Cruise's action franchise which began 19 years ago, opened with a better-than-predicted $56 million. "Vacation," on the other hand, opened much worse than expected. The attempt to reboot the 32-year-old franchise earned a disappointing $14.9 million over the weekend -- and $21.2 million since its Wednesday debut.



Why did the two films fare so differently? Here are six reasons to help explain when nostalgia works at the box office and when it doesn't.



1. Be Consistent



The five "Mission: Impossible" films haven't just hit upon a winning storytelling formula and an appealing repertory cast that includes Ving Rhames, Jeremy Renner, and Simon Pegg. They've also been consistent in their level of craftsmanship. Each one has had a different director, but they've all been top suspense storytellers. So the franchise as a whole has two decades worth of good will to carry forward.



The five "Vacation" movies, by contrast, have been wildly uneven in quality and at times even forgettable. (Quick, name someone, besides original "Vacation" director Harold Ramis, who directed any of the movies in the franchise.) So that good will isn't as strong, and neither is the sense among potential ticketbuyers that the latest installment is worthy of their box office dollar.



2. Don't Wait Too Long



Granted, it's hard to say how long is too long. After being dormant for 30 years, the "Mad Max" franchise came roaring back to life this summer with instant classic "Fury Road." Then again, "Magic Mike" and "Ted" put out sequels after just three years, and both underwhelmed. Still, "Mad Max: Fury Road" was universally acclaimed, while "Magic Mike XXL" and "Ted 2" were, uh, not. So execution is important. Nonetheless, the fact that the last "Mission: Impossible" was four years ago, while the last "Vacation" was nearly two decades ago, gives the action yarn a clear advantage over the road-trip comedy.



3. Star Power Helps



Say what you will about Tom Cruise, but even Americans will still flock to see him, especially if he's in a new "Mission." "Vacation" star Ed Helms may be popular from the "Hangover" movies, but only as part of an ensemble. He's not the draw there, and studios now know they can't really bank on him to carry a wide-release as the lead.



4. Ditto IMAX

"Rogue Nation's" jaw-dropping stunt work, particularly Cruise hanging off the side of a plane, seems like a natural draw for IMAX viewers, No doubt the IMAX surcharges helped boost the film's take this weekend.



5. Action Films and Dramas Reboot Better Than Comedies



Maybe its because laughter depends even more on surprise than drama does. Or maybe it depends more on language and less on spectacle. Or maybe it's just easier to shock and startle viewers than to make them chuckle. Comedy also tends to be more culturally specific than drama, so there goes the overseas audience.



6. Attract the Kids



This is much easier to do when the movie is rated PG-13, like "Rogue Nation," than when it's rated R, like "Vacation." In any case, it seems counterintuitive, but it's true: to succeed, a nostalgic movie needs to attract viewers too young to have much nostalgia for the title. Oldtimers alone aren't enough.



This is one reason why "Jurassic World" succeeded. All "Jurassic" needed to attract younger viewers was the spectacle of giant, ravenous dinosaurs. The sequel provided the right amount of nods to the beloved first film, while virtually ignoring the other sequels that people didn't care for much anyway. "Terminator Genisys" trashed its own mythology, too, but it trashed the key parts that people liked. All that was left was the attraction of Arnold Schwarzenegger's return to the franchise after 12 years, and while that appealed to older fans, it wasn't enough to make younger viewers care.



August will offer an interesting test of these lessons in the proper use of nostalgia. This coming weekend, we'll get "Fantastic Four," a reboot of a Marvel franchise just 10 years after the launch of the original, which has been hampered by bad buzz for most of this year. On August 14, "The Man From UNCLE" hits theaters, an adaptation of the 1960s Cold War TV series that no one under the age of 50 remembers first-hand.



Then again, "Mission: Impossible" started out as the adaptation of another '60s spy series -- here's hoping the audience that showed up for Cruise's films will do the same for "UNCLE" and the remainder of summer's nostalgic slate.