Hey actually part of my job is designing traffic signal plans. The average yellow light only lasts 3-4 seconds. They'll sometimes be longer for larger intersections, like if you were on a side street crossing the Boulevard, but 6-7 seconds is pretty excessive.

The yellow light is followed by an all-red phase thats usually 2-3 seconds, before changing over to the next phase. Some old signals in the city don't have the all-red phase and jump immediately over to a green for the cross street.

Alright sweet, now I feel like I have some sort of quasi-expertise. Hope that helped.