I feel like I’m holding people back at a drive-thru if I check to make sure I have the correct order and condiments. But then, it’s just as easy to pull into a slot and check then go back if something’s wrong with the order.
I often pull a past the window then stop the car before I am back in the parking lot and then do a quick check of my order. If its wrong I can then park in the lot and walk back in. I try to make the check very quick so I don’t hold anybody up. Also I don’t feel comfortable inspecting the bag in front of the window person...because it sends a message that I don’t entirely trust them to get it right....although its the truth, I don’t entirely trust them to get it right, seems impolite to be obvious about it.