Remember, our goal isn't to have them pay off their debt. It's to make more money. The best way to do that is to have the minimum payment about equal to the interest charges. That way we keep the payment 'affordable' and the debt plan goes on forever. There is one problem that we'll need to watch to protect our profits.
Some customers spend too much and get in over their heads.
Then we need to change our strategy. Initially, we'll increase the interest rate we charge the customer. After all, there's a greater chance that they won't be able to repay the debt. We need to cover that additional risk. Finally, if a customer shows signs of being unable to continue timely payment, we'll need to try to collect the total amount due as quickly as possible.