Except amber doesn't mean yield or slow down (not in Canada anyway). It means stop (at a regular 3-light intersection). The only difference is that you have to evaluate whether or not you can make the stop before the line. If not, then go through.

Any green that you do not see actually becoming green, is a stale green. You should be approaching the intersection anticipating the amber to drop. There are a few cheats in some areas of Southern Ontario so you know when things are about to happen (light behaviour isn't the same in all areas so it works best for regular commuting).

Some of the pedestiran signals flash or change just before the light is about to go amber. If the pedestrian signal is set to "walk" you are safe in most places around here, because it will first have to switch to a don't walk (hand) and wait around a bit before the traffic light goes to amber.

Bruno