I don't think it's all that uncommon to see in houses with recessed light fixtures, 1970s-90s type stuff. Couple 3-ways for hallway lights (also controlled elsewhere in the hallways), 1 (or 2) for ceiling fan (2 if it has lights and wired as such), rest for banks of recessed lights so someone could use lower wattage incandescents in some. I think this nonsense mostly died out with shag carpeting tho