We can only logically assume that they are trying to cover a large land mass or protect several cities or towns and areas at the same time and that these people will not work 24/7 and likely be rotating on and off of schedules.
This becomes far more believable when you start taking in the deployment into consideration.
I’m sorry but you do not sound like a coffee person. I cannot comprehend a world where I live in where I get tired of my beverage of coffee after 15 minutes because it became disgusting.