When I was film based for weddings, that was a big plus using medium format with removable backs as I could change backs for different types of film. That's when I needed someone just to keep up with unloading and re-loading film, having backs ready to use. I brought a large cooler to each gig for the film. For 35mm I had a couple of cameras, one with color and another with B&W, but I used medium format most of the time.

Much simpler and easier now as I get everything in a backpack with back ups and a few other things in my Pelican case. My lighting is all off camera and all flashes are battery operated. Smiles!