I'm on the side of DanFromDetroit. I may wash the bike a few times per year. I make sure there is no sand on moving parts and the mechanical parts are perfectly lubricated.
In the Fall, I usually apply a thin coat of grease under the bottom bracket, headset and other exposed parts and leave it that way throughout Winter, which means a thorough clean up in the Spring. I also do one or two "mini-clean up" of the more accessible tubings so I can grab the bike without fear of getting dirty.
Regards,