If you add a depot trains go to if no station is available (and they are not at a loading station) you can have a bunch of extra trains prepared and don't need to do exact adjustment every time you build a new station. If you don't see a train in the depot just put down 20 more and forget about it ...

All my train stations are named "[item] Pusher" or "[item] Receiver", with circuits to disable the station when it's empty/full. I have train groups that are named "[item] Supplier" to move each item type.

I created a wildcard interrupt that triggers when a train has any items in it so it goes to ...