That's a bit of an oversimplification. For the best results, you'd need not only three in-camera separations, but at least two color correction masks, and generally
three highlight masks. That at total of at least eight exposures. I've heard of people doing as many as fifteen exposures for dye transfer. But generally, it's been done off chrome film. TMX100 is an excellent separation as well as masking film. You don't need the old Super-XX or Pan Masking film. You do need a sizable film budget.