Station Nr.1 - two people (A and B) running together to get on the train. Immediately after A jumps on the train the door closes in-front of B's face and it stays on the platform with nothing else to do but to wait for the next train.
The destination is station Nr.9 and it takes about 20 min to get there (each stop approx 2 min).
The trains run every 2 min.
A and B likes to be together.
B doesn't have a phone.
A gets off at first stop. B gets next train, which A gets on at his station.
Or as long as A gets off and on to next train somewhere and B gets next train they will arrive at the destination together, but first stop gives most shared time.