I clean them all the time.
Fascia by hand with a cif like cream cleaner and then pure water rinse off - off either a Niftylift or scissor lift. You wont get the streaks off from the ground!!!!
Soffit/underside by extending pressure wash lance - from the ground.
Rinse down all pumps and then wipe excess water off pumps.
Dependant on size - small to medium should be able to do in one night on your own. Large one possibly two men for one night. I can just get a large one done on my own in one night but that is without stopping and I know about it the next day!!!!.
Who is it for?
Rob