I didn't manage to see Groundhogs vid but going back to peter fogwills vid.I dont believe this is a good technique to use when cleaning,even on a regular clean small dirt and dust particles will still be visible on the pane and a thorough rinse is required to make sure that all small particles are washed downwards and off the glass.With the random action used to scrub the glass in the first place,i doubt the whole area was covered sufficiently to agitate the dirt,and the lack of rinsing in a slower fashion then i can see problems arising on occassions.The other thing that appeals to me is giving a certain value for money to a customer.If i am right or wrong i dont know,but i charge a fair price to do a thorough job and that means convincing myself that the glass has been cleaned and rinsed properly and not just splashed so i can run to the next job.
By the way the comparison between rushing a window cleaning job and a superfit hod carrier is nonsense...the hod carrier didn't have to justify to the customer that the bricks were clean when the job was finished.