My hybrid used to get washed every fortnight, then slowed down to once a month, and then bi-monthly. Then I converted my old hack racer into a fixed gear commuter, and that hasnt been washed since it has been refurbed/resprayed, just the occasional wipe down. Chain cleaning on the fixed is simple wipe and lube, with a rare rinse in spirit. I certainly dont miss scrubbing the filthy cotters on the hybrid with a toothbrush!
I'm much happier just enjoying my fixed ride, rather than waste evenings and weekends maintaining/cleaning the geared bike.