I agree with the Pm one, maybe decrease to two minutes, although the 30 second should stay.
Besides, I think it should be increased to 40 seconds.
So people actually have to wait and think about what they post. Not just going around saying only things like LOL, or
, or ROFLCOPTER! Like.. It would give time enough for an actual post. None of those posts just to increase post count.. I mean if someone funny happens, type LOL, and then something relevant. Not just LOL!!