This may really sound crazy, but hear me out.
I completely agree with you that in the age of digital photography and mobile phones, the idea of spending a year on just film is really insane. But on the other side of things, I believe spending a year working with film is one of the best things many photographers can do for themselves and their work. After a year, you return to digital and you’ll realize you’re a completely different type of shooter and that you as a photographer have changed greatly.
You Will Learn About Creative Vision Much More
With digital photography, it’s really easy to just snap away at photos. So many people do this; they simply capture instead of create. But with film you’ll get far less photos than the amount you can store on an SD card. You’ll be hard pressed to make those images count or you’ll just end up giving up. There’s 24 or 36 images on a roll of 35mm film. But then try medium format; you’ll need to stop down your lenses more, be a lot more careful, etc.
You’ll Learn About Lighting and How Colors Affect Your Scenes
For a really long time, I’ve felt it nonsensical to shoot film, scan the image and then edit the image. Some labs like to scan the photos HDR style in TIFFs to give photographers the most versatility. But in that case, why not just shoot digital? It’s more than good enough for spending time in front of a computer and editing. With film, you’re shooting so that you don’t need to do that. It will teach you about color filters, how the light bouncing off of a brick wall will affect a scene, how much you may prefer black and white’s simplicity, etc.
You’ll need to be content with what you get right from the film and you’ll need to learn about how colors work, how lighting works, etc.
More than anything else, you’ll fully appreciate the fact that you’ll need to become more than just a natural light photographer or one working with constant lights.
You’ll Learn to Work Within Limitations
How does shooting an entire roll of film at a single ISO setting sound to you? Or only working with Daylight film in a tungsten based environment? You’ll learn to read light! This was already said but it needs to be hammered in.
You’ll Learn to Not Chimp the Camera and Interact With Your Subjects More
With film, there is no chimping the screen. It’s just about shooting and moving on. You’re not going to see the images and you’ll instead get them much later after development. So when you go back to shooting, you’ll learn from your mistakes better and they’ll stick with you due to the stakes being higher. You’ll also learn how to interact with your gear less and with your subjects more.
You’ll Understand Your Own Tastes Much Better and How to Work Better in Digital
When you finally return to digital you’ll have a more developed creative vision, you’ll understand lighting, you’ll understand working in limitations, you’ll appreciate how color works and adds to your images, and you’ll overall just be a better shooter.