I find one way of picking up a couple of extra's is to tell a customer, [usually the last one of any chosen day], that you are short of time, and "Can I pop round and do you on Saturday morning?"
Go round on Saturday, park where everyone can see your motor, leave a bucket on the roof, for the really dim, and take your time, particularly at the front.
People who are normally out at work on the day you normally call are usually at home Saturday mornings.
They will often ignore a flyer, but if you are standing there, as large as life, and twice as ugly, [except for the lady W/C's amonst us, of course!]......
Try it, I got two only this morning.
It was because I got rained off on Thursday, just as I was halfway through the penultimate house in this case, but the principle is the same.
Window Cleaners with principles?
Baldeagle in Staffordshire.