This prevents you from wasting time chasing down your check after you've already given them their product. To ease the collection of money, get a deposit before hand and get the last check before the final installation. In some instances, it is better business to fire a customer who is reducing the profitability of your business. Chasing after your money costs you money. You hate to turn away any business, but you need to get full value for your products and services with as little time-consuming aggravation.
Time is money.
That customer requires so much attention. He expects special treatment. Then there's the installation. The universe and Rome went up faster. In his case, make sure that you bill all of the extra time that it took you to redraw proofs and designs and for what the wasted materials cost you.