We manage it with over 300 hundred monthly clients.. and no full time bookkeeper. Yes, it takes some time.. but doesn't everything that we do everyday??? We set up automatic invoicing for every monthly customer and set to email out automatically once the invoice is generated. The ones who are on recurring CC payments get charged and we get notified. The only accounts that take excessive time are manual printed and mailed clients that don't use CC's.. which we make sure are few and far between by offering incentives for auto CC billing.