Nah it don't take 13 min to get to grand central by subway and shuttle lol from Penn. First need to exit the train then walk thru Penn...sometimes getting off the train and walking up the stairs to get off the platform takes several minutes... next to the subway turnstile ...that takes time then walk to the subway platform, Only if extremely lucky the subway arrives as soon as you enter the platform, walk thru time sq sta and the shuttle is waiting for you as soon as you sit down it leaves. Exit the shuttle and walk to grand central ...No subway or shuttle delays also that would be a great day. I would def take an escalator ride over subway/shuttle from penn