Collections starts before the sale
A business with a serious receivables problem usually has an order acceptance problem. Orders are taken from customers with no agreed limit, terms are assumed rather than agreed, and existing overdue balances are visible to nobody at the moment the next order is accepted. By the time the invoice ages, the exposure has already been created and the only remaining tools are chasing and goodwill.
The single highest value control is therefore a check at order stage: agreed credit limit, current outstanding, and anything overdue. Where those three are on the customer record and checked automatically, exposure stops growing quietly. Where they live in someone head, it does not.