Me: "But surely it makes sense if we are being invoiced monthly then we should invoice monthly?"
Dave: "No, it's too much hassle to invoice every month. We'll invoice once a year!"
Me: "But if they cancel then we'll have to credit the remainder? Plus you'll need to keep on top of who's had what and when at the year end when you say you'll invoice? Effectively your invoices will be all over the place as you invoice different customers at different times? At least on a monthly basis all relevant customers are billed at the same time regardless of join date?
Dave: "You don't understand, it's too much hassle."
Three months later
Dave: "We're going to start invoicing on a monthly basis."