I'm somewhere in the middle. I ride my bike every day and I don't clean it every weekend. I do keep the windscreen, mirrors and headlights clean though. Every 1-2 months I will go over it with a bucket of water with a few drops of soap and wet rag it, but I have only done one proper washing with a hose since I've had it. Well, that isn't counting another proper washing where I intentionally rode it in the rain to clean it. That did the best job of all.
I think overwashing is probably more damaging to a bike's finish than under washing though.