mine gets done probably once every six weeks in the summer and once every two - three months in the winter. I waxed it a couple of weekends ago; it needs another coat and then it will have to be enough until Christmas or Easter, depending on whether I have access to a hall at Xmas or not.
I don't wash it in the winter much, there's no point. I'm off to Tampere in October for two days - that's 125km each way times four - and if it's icy and around -2, which is what I'm expecting, then the car will be black by the time I get back. The way things run around here... I'll blast it with the power washer occasionally, but had an incident last year with the water freezing on the panels........ oops. When it's below about -10 for two months, it stays pretty clean anyway.
Waxing / SRPing two-three times per year is plenty IMO, washing every couple of weeks with 2 buckets is almost reasonable
I'll admit here that I have two cars to look after at the moment and neither shows the dirt, so I can get away with three months between washes if necessary, and yes, I have done that.