if:
1. There's room
2. There's a long line of cars (7~8 or more)
3. Past the light, there's one or more of the following:
-A shoulder, so cars can easily re-pass, OR
-More backed up traffic, OR
-A lower speed area where I can keep up with traffic, OR
-My destination or a road where I'm turning off.
Actually, one exception was where a bus was loading on a one-lane road with a median (so no cars could get by). There was a visibly massive crowd waiting to get on the bus, so I just passed a couple cars and the bus on the left.