It all depends on the riding conditions. Also washing the bike and cleaning/lubing the drivetrain don’t necessarily have to occur at the same time. Some general ideas are that if the drivetrain has a lot of dirt and grime its probably time to clean it. If you crank the pedals by hand and you can feel that it isn’t running smooth then clean and lube. We deal with a lot of sand in my area so it gets into the lube and creates a gritty paste that will wear out the components quickly if not taken care of – and thats even with running a "dry lube." Also, low pressure water and a wipe down (don’t put your bike up wet) is fine if the bike is dirty muddy. Just include cleaning and lube for the important stuff. They do make bike wash soap (but I don’t use it) and dish soap apparently isn’t too great on the components because it allegedly affects factory coatings. But I’d be lying if I said I knew that was fact and plenty of shops recommend it. Whichever way you choose to go just keep high pressure water out of it so nothing gets forced into the bearings, components, fork seals, headsets, hubs, etc.
I would recommend consulting your LBS on what they suggest for the people who ride in your area and conditions. Basically, if you ride in wet/muddy conditions, dripped a buckets wort of sweat on your bike (it’s salty and corrosive), or if it’s starting to look like you have never washed it before…….wash away.