I can't imagine going to that extreme every time, but once or twice a year sounds OK.
How do you clean your cassette? I had problems shifting last summer and it turned out to be road grime on the cassette, rather like the stuff that gets on you car wheels like brake dust. It doesn't just wash off. The mechanic had to scrape it off. Somebody suggested I use car wheel spray cleaner every once in a while. Probably need to do that now.
How do you clean your bike when it's cold? Can't rinse it off with the hose???

