I collect Sunday afternoons, most people in then. A few pay online and in each area we clean, we have a custy that takes on the envelope payments that we leave if we can't catch someone in. We reduce her price for doing this by 2 euros. Works OK but there are always the odd payment dodgers, they get replaced.
All German custies either pay on the day, or we send them an invoice with 10 days to pay, got no German bad payers.