Prospective pizza driver David from Michigan wrote, How do you learn the areas and is a GPS unit a practical tool?
Our store had a huge wall-map with a grid. The computer assigns the grid to the delivery ticket when the order is placed over the phone, so we know where to start looking. In about 2-3 months you will have a pretty good idea where 95 % of the streets are in your area.
A GPS may be handy at the beginning, but I would not rely on it. Learning the streets yourself will help you to know what goes together as a double. Also, the time it takes to key in the address will slow you down.
What would be really cool is to have the address barcoded on the delivery ticket, so that you could just swipe the ticket with a portable barcode reader in your car, and have the address entered into the GPS automatically.