See, now I know that you are a furrerighner.
Because the only people that care about this "timetable" thing are foreigners and the New York Transit Authority that runs the trains. Anyone who lives in NYC knows that if you want a subway train, you go into the subway system, and a train will come. It will come sooner, or later, or sooner or later, but it will come.
The NYTA goes way out of its way to try to make trains stick to schedules. They have lines that will take a few hours to get from one end to the other, and they REALLY WANT TO BE ABLE TO REPORT THAT THEY MADE THE SCHEDULE. So, if a train starts running behind, NYTA will inconvenience literally thousands of passengers who are just trying to get from one station to another station maybe 6 stations away (or 15 minutes away) by turning a train that stops at all stops (a local) and making it SKIP STATIONS so that somewhere in the jungle which is its final stop, that almost no one is at, it can arrive on time. And the passengers then have to wait another ten minutes.