Some are over 2 months overdue. I was talking to one when I was there doing the windows and told them it was 2 months. As far as letting them pay when they want and some if you having 509_1000 debt, more fool you, customers can't go to the supermarket/petrol station/vehicle repair garage and pay when they like,so why should they be allowed go do it sits window cleaners?. A plumber it any tradesman coming to work in your house will want paid on completion of the job. Give them an inch zeds they will take a mile. I am a sole trader and that is too much to have outstanding.
Rolling debt is rolling debt, i dont know why you are afraid of it. You sound nervous that you are not going to get it.
I regularly have £1000 outstanding which may sound alarming but really its not. I dont let anyone go more than 1 clean without payment.
I just dont stress about it, im not constantly checking my account everyday to see if that payment had come in yet.
I sit down once a week on a sunday and mark off payments and send a text to anyone thats been cleaned more than 7 days ago. It sorts itself out because if by next clean they havent paid they are paused given a few more reminders then if still havent paid they are off the round, debt letter sent and replaced.
If you are that bothered use go cardless, personally i decided the go cardless fees were not worth paying.