Can I clear something up here? Cuz this topic is a bit more complicated than anybody is admitting:
It's about how you take cs.
For example:
a) If ally is gone (and wont be back soon) and enemy is still in lane, you are to last hit only. If you push the wave, the enemy has a chance to freeze wave on their side and you effectively screw your ally over when they come back to lane.
b) If both ally and enemy are gone (and neither will be back soon) then hard push the wave. If you force it under tower at a time where the tower wastes the xp and gold without stalling the next wave, then do it. You force the lane to be reset at the evenly pushed mark and cause the enemy to miss out on a wave of xp/gold.
c) If ally is gone (and wont be back soon) and enemy is on the way back, last hit only. These are for the same reasons as example a
d) If both will be back soon, last hit only. These are for the same reasons as example a
Now obviously there are exceptions and these are situational example, but use your head. If you can't push the wave fast enough to reset the lane, or the enemy jungler is around to freeze lane for the enemy laner, or etc etc etc, be smart about it. Don't be that douche jungler that hard-pushes every lane to force your ally into a gankable position just to cs.
Sincerely,
Slythion
P.S. - I hope this cleared it up for those who didn't know this stuff or any new players that are just starting jungling