That fact that The Revenant was shot with natural light is unusual for any feature film, even less with one of this scale and budget. Another thing unusual about this film is it was shot in chronological order. But in the video below director Aljandro G. Inarritu says that it’s not that unusual for him to shoot chronologically.
“Every film that I have done since Amores Perros I have always shot my films chronologically—all of them. That’s the way I shoot, and that’s the only way I understand the story, and the characters, and that’s the way I leave room for the story to be growing. For me to understand it, and to be making changes according to what the story is driving me to do. As a filmmaker you sometimes you are god, and sometimes you are a creature of the thing. You have to be humble sometimes to hear what’s going on and what transformations are these story requiring, and you have to be serving that. Sometimes the film takes a power in itself that you have to be observing, and at least for me—as director and producer—I have learned when I leave room for that to happen correctly, there is great abandonment [unsure of word used] in narrative, in actor’s approach, the crew, everybody’s growing as we are doing….Even when the films were structurally built in a very complex way, every story I did chronologically. Even when it cost a little bit more—and I always said I was not investing or spending money on visual effects [but] emotional effects. And I think the emotions of the actors are better achieved when the actors understand the chronological and emotional factors that are adding to the story. And it this case particularly, the story of The Revenant starts in the late autumn and ends in the deep winter, so there was no way even if I decided differently to shoot this time, I could not have done it—I couldn’t have shot in the Autumn, let’s say, a scene of the ending of the film that requires a lot of snow.”
Aljandro G. Inarritu
P.S. Here are a list from memory of movies where, if I recall correctly, the filmmakers (usually the writers or directors) allowed room for the stories “to grow” while filming and quite effectively changed the ending of the movies; Birdman, Chinatown, Casablanca, and The Shawshank Redemption.