They're fast compared to Subway because Subway has something like 50 things you can put on a sandwich and it seems like 1/4 of the customers get all 50 things loaded on it.
I always wonder if you get mayo, mustard, ranch dressing, hot peppers, oil and vinegar, avocado smear...and 50 other toppings on a sandwich, how do you chose which sandwich you want? They'd all taste exactly the same.
Same thing at Chipotle, seems like half of the people get every single topping possible. Chipotle could add 10 more toppings and they'd get 10 more on it.