This is, it should be pointed out, a fairly recent development. Scan the 10 Best Picture winners before No Country For Old Men, and you'll notice only two of them, American Beauty and Crash, came from Venice or Toronto.
Lots of factors are at play here, from shifting tastes to changes in key festival personnel. But there's no question that with more films for audiences (and awards voters) to chew on than ever before, having the right kind of launch, and tracing the right kind of arc, have become instrumental parts of being noticed.
An example for the ages was La La Land last year: the Venice opening night film and the winner of the Toronto audience award, it was the presumed Best Picture front-runner right up until Warren Beatty and Faye Dunaway tore open the envelope, and arguably for a few minutes after that.
True, it may not have actually won, but its commercial performance, built entirely on its must-see status forged at Venice and Toronto, presumably went some way towards making up for it. This independently made musical took $620 million worldwide more than every blockbuster in the last four months, apart from Guardians of the Galaxy Vol. 2 and Dunkirk.
All of which is to say that where the coming Oscar season is concerned, a shortlist of serious players is about to snap into focus. (Some UK release dates for the below have been set, but most are still TBC, in part because distributors will wait to see how they play at Venice and Toronto first.)
This year's Venice opening film is Downsizing, a science-fiction-inflected comedy from Alexander Payne, the director of Sideways and Nebraska. Starring Matt Damon, Kristen Wiig and Christoph Waltz, it's about a married couple who have themselves shrunk to pocket size.
Opening Toronto has historically been a less auspicious gig, but this year's sporting biopic Borg/McEnroe might change that - though I gather Battle of the Sexes, with Emma Stone and Steve Carell as Billie Jean King and Bobby Riggs, is the 2017 tennis film to beat. (It's directed by Jonathan Dayton and Valerie Faris, who made Little Miss Sunshine, and was written by Simon Slumdog Millionaire Beaufoy.)
The films screening at both festivals are often the ones that have awards-watchers bristling with anticipation, and none look bristlier than Mother! - a thriller from Darren Aronofsky, with Jennifer Lawrence as a housewife whose home is invaded by a series of odd visitors, seemingly with the consent of her husband, who's played by Javier Bardem.
Striking a different tone, you'd imagine, is Stephen Frears' Victoria and Abdul - perhaps a spiritual sequel to John Madden's Mrs Brown, with Judi Dench reprising her Bafta-winning role as Queen Victoria, now platonically besotted with her young Indian attendant, Abdul Karim.
Both are currently scheduled for a UK release on September 15, capitalising on festival buzz.
Andrew Haigh will bring the follow-up to his superb 45 Years, a horse-training drama titled Lean on Pete, to both festivals - and Martin McDonagh, the British-Irish director of In Bruges, will do likewise with his dark comedy Three Billboards Outside Ebbing, Missouri, featuring Frances McDormand as a grieving mother who goes to war with her local police.
Joe Wright's Churchill biopic Darkest Hour, Andy Serkis's Breathe, Clio Barnard's Dark River and Armando Iannucci's political comedy The Death of Stalin are all Toronto-only as is The Breadwinner, the latest animated feature from the Irish studio Cartoon Saloon, whose previous film, Song of the Sea, also surfaced at the Canadian festival.
Both Barnard and Iannucci's films will play in the Platform strand, which last year burnished its credentials by playing host to Moonlight.
It's only fair to note that Moonlight actually showed up first at Telluride, a four-day "boutique festival" sandwiched in between Venice and Toronto.
Think of the Colorado mountain town rendezvous as the organic veg box of film culture: the programme isn't announced beforehand, and the delicious and the binnable tend to feature in roughly equal measure.
One likely dead cert for Telluride is The Shape of Water - a gothic fantasia from Guillermo del Toro, in which a mute charlady, played by Sally Hawkins, befriends an amphibious humanoid held captive in a laboratory.
George Clooney's Coen brothers-penned satire Suburbicon, and Paolo Virzi's The Leisure Seeker, with Helen Mirren and Donald Sutherland as an elderly couple on a life-crowning road trip, probably won't make a stop in Colorado, though that's not necessarily a sign of trouble.
Nor is the appearance of a Netflix film, the Robert Redford-Jane Fonda reunion Our Souls at Night, at Venice: this venerable festival has embraced television, online streaming and even virtual reality with a warmth those mediums have yet to encounter at Cannes.
Of course, the full picture won't fuse until after the festivals themselves have faded from view.
One of the presumed-heftiest Oscar contenders-in-waiting, Steven Spielberg's Nixon-era newsroom thriller The Papers, seems unlikely to screen anywhere until December.
Paul Thomas Anderson's Fifties fashion-world drama Phantom Thread, another December release, features what will reportedly be Daniel Day-Lewis's final screen performance.
Christopher Nolan's Dunkirk has already set a nosebleed-inducingly high bar for the 2018 battle for Best Picture. But few things are less gripping than a foregone conclusion, and the race is about to get interesting.
