Passing doesn't save much time when the city you're in has a ton of long red lights, There's a highway I travel daily, rather short 12 mile lap. People will absoluty blast past me going 20-30 above the speed limit, and then 10 minutes later they will be right infront of me at a red light. There's no point in making your ride so much more dangerous just to shave a few seconds off your time.
I also have people pass me, merge back in, and then brake hard to turn off pretty fucking often on this commute. It's insane what people will do.