What I'm saying is that, sometimes people will say "yes" because they don't like to say "no", also you get the ones that only want a one off clean and they know that if they say that they might not get them done. Then there's the "cast off's" that other window cleaners don't want because they're messers or bad payers or access problems or any other reason they were dumped.
Don't get me wrong, I'm not saying that they're all like this, but I will be surprised if he still has all 15 in 6 months.