The purpose of the countdown clock is to provide information about that "unexpected delay". The clock is irrelevant if the trains are arriving every 3-4 minutes

The purpose of the countdown clock is to provide information about that "unexpected delay". The clock is irrelevant if the trains are arriving every 3-4 minutes. Think of this being an autoscaling group. The argument that people make sounds like "Well, autoscaling group works fine when one instance can handle all the traffic. We are happy with it." It is not an achievement to have an autoscaling group work when it has one instance in it.