I'll blow a light if I don't see anyone coming but my judgement for "someone coming" takes into account my own somewhat pathetic acceleration and the sheer number of moron drivers that don't know what the stalk on the left of the steering column is for. As a result I usually end up stopping anyway, even if it isn't for the whole light. Heck, around here I've found it's safer to cross against the lights. Car drivers just don't pay attention to small traffic on the right when they're turning.