About 14 years ago, changing carrer, I became a city bus driver (and Montreal is a big city).
One of the first thing we learn, is that accidents generally happend, mostly : when you are changing lane, and at intersections.
From that moment, I stopped changing lane so often. Most of the time I will simply adapt my speed to the vehicule in front of me, at least for a few minutes. Often times, this vehicule will change of lane, or I will finally pass him whithout hurry, and when it is real safe to do it.
And now I can see just how much lots of drivers are constantly changing lane, even zigzagging between cars, sometimes at highway speeds.
When you have 2-3 lane or more, going in the same directions, there are contraction and extension zones going on constantly, moving like slinkies.
So, as soon as it slows down, we want to go in the other lane that moves faster. Until this lane start to slow down too. And then you have to change lane again.
But at a larger scale, in some circumstances (say heavy traffic going slowly on all lanes), all lanes are going at about the same speed.
Changing lane is a bad habit.
But sometimes we have to.
