I don't have a car, so always inside. Less than 30 seconds. I read the menu before I get in line, preferably on my phone ahead of time.
We have a baguette/sub sandwich shop here, which only has one till at the start of the counter, and as your order is prepared you walk along the counter to pick your veggies and whatnot. I'd guess it's a common format, but for the sake of clarity: you go to the till and order the "wrapper" (sub, tortilla wrap or toast), meat (chicken, meatballs, ham, lots of variants) and extras (cheese, extra meat). You pay, and walk along and tell the next person what free stuff (veggies, sauces) you want in it (and repeat your order if there is lots of traffic).
Even if they have an infinite line of regulars in front of them to learn from, who all know how the system works and how to order efficiently, there are people who can't grasp this concept even if it would win them a billion dollars. They will tell the cashier their entire order, some veggies they want, where they want the veggies placed, that they don't want tomatoes, why they don't want tomatoes, and at least two accounts of how they severly messed up their order five years ago. Only to repeat it again to the next person who actually deals with veggies.
I've seen this happen with families, two parents and four kids. The number of seconds a kids order is consistent is equal to how many years old said kid is. If you are a happy couple, for the love of god don't bring your kids with you to place your order. If you can't keep track of six orders in your head, tell your family to order less complicated, or eat cheaper at home and buy memory games for the money you saved.