Rush hour direction can be thought of toward Manhattan in the AM, and to the outlying boroughs in the afternoon. While trainspotting at Roosevelt Avenue around the PM rush, it was common to see Jamaica-bound E trains almost filled to capacity, while the trains going to Manhattan had the typical, passenger loads. This pattern was also noted at Atlantic Av, on the 2.
There are also "rush hours" within Manhattan. A classic example is 34th St. on the 8th Av line at 8:00a. Once an NJT train dumps the crowd onto NYP, it's a rat trap right past the turnstiles, with instances in which I had to wait for a second E train because it was impossible to get into the first one. Most of these detrained (with much relief!) at either 5 Av/53rd or Lex Av to go to the business districts there, while a nearly empty E train went on to Queens.
DANGER - DO NOT GET OFF MOVING TRAIN