As a cash strapped teenager who was very excited by the prospect of working on and maintaining my bike, I was warned in very strong terms that you should never
pressure or jet was a bike. The argument was that a high-pressure nozzle would force water past the seals and trap moisture where it didn't belong. This can then lead to corrosion, rust and a whole litany of other problems. I remember working in a bike shop about 10 years ago and we had a customer that was so eager to use the car garage-grade pressure washer to clean his bike that he, on more than one occasion, cracked rear ends because there was so much bind and stiction in the linkage of the bike.
However, on the other hand, I feel this is an area that has gotten significantly better in the last five years or so. It used to feel like washing your bike was simply a way to introduce another noise. Now, conversely, more and more linkages seem to be genuinely watertight, and gone are the days of seeing red or blue seals protrude around the edges of frame hardware. Headsets have also got better in this regard. In fact, Cane Creek now sell their Hellbender bearings, which itself borrowed from technology in food production to stop bearings from contaminating sausages.
Personally, I wash my bike with a turned-down pressure washer a lot. I hate starting a ride with an already sullied canvas. But, it should be worth noting that I'm almost fanatical in this regard. Helmets, shoes, and bike all get a good clean after every ride. I just feel like a well-maintained bike that looks as good as it can is one less thing to rub away at your motivation as you try and get out the door. I also just accept that me getting merely 5 and not 5 and a half months out of a part is going to come with the territory.
On the other hand, a bit of mud on a non-moving or loading surface never hurt anyone, and if you can help it, as long as moving parts are clean, should we be washing them at all?
There's a big difference between using a bucket and brush compared to a mains-powered water cannon, even if it has been turned down. How often do you wash your bike, what's your method of choice, and how do you feel about pressure washing bikes in general?