I think a big source of this problem is the traffic in the right-hand lane that turns left. Every day, the same vehicles are in that lane and fight to get into the left-hand lane once they make the turn. It's not people who are lost or confused. It's people who want to beat the system and beat the light by skipping ahead of all the traffic in the left-hand lane. Inadvertently, that causes significant slowdowns and limits the amount of traffic that can get through in a reasonable amount of time.