There are no hard and fast rules since urban traffic is a complex system. Going faster can give you some space, or encourage aggressive riders/drivers around you. Not a good situation if they (or you) have poor skills. Sometimes holding position behind a slower bus/truck lets them pass and duke it out someplace ahead, where yet another red light/jam awaits. Lowering average speed to reduce slowing/stopping and smoothing out the kinks can be pretty satisfying. Plus, it can give you extra reaction time to deal with the turkeys, who will try anything to save a few seconds.