Left-turn traffic signals staying green for much longer than necessary...

I'm finally fed up enough to post this... the protected left-turn traffic signals in Southern OC are maddening sometimes... there are intersections where they stay green for almost 2 minutes just to let 1 through... sometimes, that 1 car is just a ghost, & regular traffic has to just sit there with no other cars in sight... sounds like a minor inconvenience until it happens to you at that same intersection every day for the next 3 weeks... is this caused by faulty pressure sensors or some sort of traffic engineering tactic to slow down your commute? I typed this entire thing while waiting for the light at El Toro/PDV to turn (just kidding)...