I once worked out how many panes were on a job (3750).
I got bored, It was well before wfp came along. They are about 4" by 6" each and all needed to be cleaned trad in and out. A seriously dull couple of days.
I wonder if the sign writing has paid for itself. It probably took a while to work out that 3 million panes were being cleaned. Somebody would have to sit and think about all the jobs and how many panes each one had etc etc. All that counting takes time.