I don’t think our systems can cope with everything running. But if you do it as SimCity 4/5 with regions, where you build up a city and then it generates traffic when you play other cities and send traffic to them.
If you couple that with time tables then the intercity A -> B express train will arrive once every hour, or whatever time system they might implement.
Instead of micromanagement and mouse click fest I rather work with something complicated that require more thought then mouse clicks. A few trains, signals, switches, and building a time table.
If anyone who has the skills fix a mod so we can select the route for a train, and that the mod hold the train at the station until it is time to leave.