As summer draws to a close, studios are pondering the contradictions of the season. They’re celebrating the films that performed — mostly toons and family-friendly fare — while questioning why grosses have been essentially flat. According to NATO, admissions are down 8%.

While “nobody knows anything” is as true this summer as anytime in Hollywood, there are a few lessons to be taken away from the summer’s hits, misses and middling movies:

With “Inception,” a pic that normally would have justified a more expansive day and date rollout, Warner decided to go only in the U.K. day and date. Since its release, however, Warner mounted an aggressive rollout strategy to benefit from a more ripe summer playing field. “Inception” has reached $387 million in foreign B.O. receipts.

In general, though release schedules were altered, the international B.O. didn’t suffer much from the World Cup, with counterprogramming moves paying off.

Summer B.O. totals stand at $4.04 billion as of Sept. 1, compared to $4.17 billion earned during the same period in 2009. And since Labor Day Weekend isn’t usually a blockbuster weekend, the season’s totals look unlikely to surpass last year, which saw an extra week of play time.

3D vs. 2D. Auds continue to question the value of multiple dimensions: 3D pics’ opening weekend shares have declined steadily since “Alice in Wonderland” earned 71% of its debut from 3D-equipped screens back in March. The DreamWorks Animation “Shrek” sequel and Disney/Pixar’s “Toy Story 3” took about 60% of their opening weekends from 3D screenings. U’s “Despicable Me” launched in July with 44% of its bow coming from 3D, but surged slightly with the format in subsequent weeks.

Some insiders have attributed the decline in 3D shares to the logjam of product, while others suggest auds, especially families, could be showing resistance to higher ticket prices.

Nikki Rocco, U prexy of domestic distribution, notes that while 3D helped boost “Despicable Me’s” robust $237 million gross, 2D screens also contributed more than half the total. “The 3D format is an enhancement where people no doubt love the technology, but the majority of grosses ultimately came from 2D,” Rocco says.

The format saw a recent resurgence when the Weinstein Co. debuted its multidimensional scarer “Piranha 3D,” which took in 95% from 3D during opening weekend. That’s not to say, however, that auds had much choice in the matter. An overwhelming majority of the film’s total locations (89%) were 3D.

Seasonal shifts keep franchises fresh: “Toy Story 3” marked the first summer release for the Disney/Pixar series, and the first for Summit’s “Twilight” franchise with “Eclipse.”

The Mouse House prepped moviegoers for the “Toy Story” sequel when it re-released the franchise’s first two installments in 3D last year. Most insiders say the move effectively reminded auds of a franchise that hadn’t screened in multiplexes for more than a decade, without exhausting the family market. As a result, “Toy 3” became the highest-grossing June opener, with $110.3 million, and the summer’s Stateside prize winner, grossing $406 million. With kids out of school, there was even more upside potential for the four-quadrant pic.

With domestic totals at $298 million, “Eclipse” has surpassed the franchise’s previous installment “New Moon,” which wound up with $296.6 million after launching Nov. 20. “Toy Story 3” and “Eclipse” both landed among the top five summer performers.

And while Summit has decided to revert back to the franchise’s original Thanksgiving release date for the final two pics, Summit prexy of domestic distribution Richie Fay says weekday business made the summer switch worthwhile. “What we found was that during holdover weekends, there were tentpoles opening against us that clipped our weekends,” Fay notes, comparing “Eclipse” to the previous “Twilight” pics. “But the weekdays held up so much better that it was basically a wash.”

Still, seasonal shifts don’t always work for high-profile franchise pics.

In 2008, Disney moved “Chronicles of Narnia: Prince Caspian” to May after the first film launched in December with a total $291.7 million. “Prince” tallied much less overall during the summer, grossing $141.6 million domestically. So 20th Century Fox, which picks up where Disney left off with “Chronicles of Narnia: Voyage of the Dawn Treader,” will go again in the fall, with the third installment set to launch Dec. 10.

World Cup? No worries: Disney attempted to beat the World Cup heat by launching “Prince of Persia” a week before its U.S. bow; so did Par with “Iron Man 2,” which has tallied north of $300 million in foreign B.O. receipts.

Both strategies successfully added a week of playability before the soccer-induced crunch. Universal and Fox also braved the pitches this summer with “Robin Hood” and “The A-Team,” respectively. “Robin Hood” scored standout marks overseas, doubling U.S. totals, while “The A-Team” tallied more modest returns. Warner’s “Sex and the City 2” also was one of the few releases to go day and date overseas and the U.S.

Sony’s “Karate Kid,” which debuted in the U.S. June 11, has a muscular $175.9 million domestically and also saw top coin overseas with $143.7 million.

Paramount’s pricey “The Last Airbender” held up well with fanboy auds both in the U.S. and overseas, but also played well to families, grossing $252.9 million worldwide.

Audiences can handle originality, in measured doses: A clunky name and brand-new concept didn’t hurt Universal’s “Despicable Me,” one of the biggest surprise hits this summer, from producer Chris Meledandri’s newly minted Illumination Entertainment. Warner Bros. took an even bigger gamble with “Inception,” which B.O. observers feared would be too complex for summer popcorn auds.

Warner prexy of domestic distribution Dan Fellman says the film’s event potential was well-suited for summer. “We took our shot with (director Christopher Nolan), and he delivered.”

Summer auds are always looking for good comedies, and a pair of non-sequel laffers, “The Other Guys” and “Grown Ups,” delivered impressive coin for Sony this summer, grossing $100.4 million and $159.4 million, respectively.

A fresh take on a family dramatic comedy, Focus Features “The Kids Are All Right,” was the summer’s top specialty pic. After launching at seven U.S. locations on July 9 with the year’s highest per-screen average of $70,282, Focus rolled out the pic aggressively with 994 locations at widest release. It proved to be a profitable strategy, as “Kids” likely will land north of $20 million in the U.S.

Some original material had a harder time getting traction with auds. Both “Scott Pilgrim vs. the World” and “Knight and Day” stumbled in their debuts, which meant middling holdover frames would likely follow. “Scott Pilgrim” has cumed $26.8 million, while revenues for “Knight” stand at $76 million domestically.

The takeaway from summer 2011? With higher ticket prices and fewer films being released (from a high of 40 wide releases in 2008), perhaps Hollywood can be content that it’s still holding its own.