That just because the car in front of you has a momentary change of speed, you don't need to slam on your brakes. Congrats, you've caused traffic for hours

Following distance should be 1 car length for every 10mph you are travelling. 70 mph would mean 7 car lengths.

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.

Your car 100% definitely has automatic headlights, so why the fuck are your headlights off in the middle of the night??

The risk undertaken to make a short trip at 20mph over the speed limit isn't worth the few minutes it might save. On paper it seems like it would save a lot but the reality of inevitable stop lights and traffic cause different results.