I used to do some shops, trad.
The only thing that was good, was people in their cars, early mornings, in traffic jams, looking at you, wondering what you were doing, cleaning windows for a pittance. They weren't far wrong! I could clean the windows, quicker than I could I write out the receipt and get paid. Complete pain. Not interested any more.
However, I did meet a window cleaner who ONLY did shops and had it off to a fine art. He was f&&king cool.
Given the chance, I would be him!