* Does the NYC subway even have a fixed schedule during most times of the day? * They do, headways (intervals between trains) vary at specific times of the day

* Does the NYC subway even have a fixed schedule during most times of the day? * They do, headways (intervals between trains) vary at specific times of the days (large headways late at night/early morning, small headways during peak transit hours, mid-size headways during the day) and you can use those to compute the schedule. In NYCT's case, they run enough trains that in Manhattan a train comes pretty much every few minutes but in the other boroughs they may run infrequently enough that you'll want to plan ahead.