Via DC StreetsBlog, an article from Toronto highlights how bad driving habits cause gridlock. One example is how last-minute braking causes congestion,

When approaching a known congestion zone such as an accident or construction area, drivers often accelerate before braking hard once they are very near the stopped car ahead. But research shows that this approach speeds up the amount of time it takes all cars to reach stopped traffic by pushing the so-called line of zero movement further away from the congestion cause. In other words cars are forced to stop sooner and for longer. It then takes much longer for all traffic to begin moving again. A smooth traffic flow keeps the line of zero movement to a smaller area, trapping fewer vehicles.

The other points in the bullet list of ‘tips for better driving’ can basically be summed up as “don’t drive aggressively”, with the exception of the point that the left lanes in a highway should be used for passing and/or higher speeds.