I just keep in mind that local city traffic means nothing.
City-to-City trafic is a key to get money. So i use local lines as a feeder to the long lines only. My local lines end on the long range station. Therfore I make local line as forth and back, never circular. I need to transfer people from their location to the long travel port. If they need to go buy a bread to their local shop, I dont care. If they need to buy a bread in the shop on the other side of map, well, thats interesting
Local city traffic means a lot. It’s income, you can get some decently profitable lines in city if done well, and they feed city to city traffic and deliver it as well. With the 20 minute rule you don’t only need to get the person on the train, but they need to get to their destination. Good local traffic means more change for them to hit their destination and take the route again, which means greater city to city traffic.