I prefer to use a hood in most cases. They keep my lenses protected from objects, snow, rain, my fingers, etc, as well as blocking stray light.
I'm not a huge fan of screw on hoods, prefer to use a bayonet hood, but many of my lenses only use screw on, so I use them where needed.
There is a limit on how big is acceptable with hoods. For example when I got my MEM, it came with the 12575, which is just silly to use on the wonderfully compact MEM. Fortunately the compact ITOOY fits and works great, so I use that.
One lens I don't use a hood on is my LTM W-NIKKOR 3.5cm f2.5. It is so small I don't want to detract from that. Also the front element is recessed far enough that I don't worry about it getting banged or finger prints.