I looked up 3 airlines in Chicago and they have the exact same route structure! I wonder if a certain premium feature is responsible... :twisted:
Pfffft...
I wouldn't know, as I don't have any premium features.
I just look at the "view airport" screen, and take notes on where everyone else is going. Then I make routes to those destinations.

If I have any hours on an aircraft left over, I make routes with the aid of an atlas next to my computer.