How long to go between washes?

[Yetti]

I must say I am nuts about keeping my rides clean, but this winter has drove me nuts. I no sooner get my H2 washed it either snows or or warms up just enough to make mud out of my road and cover the truck. I had to go to friends house today, and his road was terrible. so when I was headed home for the day I stopped by a quarter wash to spray it off...$4.00 in quarters later it was clean enough to be seen in again.
how often do you guys wash your rides when the roads are crappy?