Both of my shops have a drive thru window. Nothing wrong with them. Customers love to use them - as long as they know about it. AC (after Covid) use has skyrocketed since we closed our lobby for a period of time. Make sure you have a good notification system. Either a motion sensor of possibly a doorbell they can ring when they pull up. A video camera on it w/ a monitor somewhere in the store is good so that you can see if someone is there and the tone did not go off. If the drive thru is convenient to the rest of the store it is a plus. If it’s far out of the way I am sure it would almost take more time to serve a customer - get their name & money, then run to get the food, then run back to give it to them.