With regard to the "traffic opening up for you like magic", of course it does. When sitting in a car, you observe the accordion effect, when traffic bunches up, then opens up, then repeats. This is due to people speeding up and slowing down, rather than just rolling at a slower pace. It just happens. When you are splitting, you tend to be between lanes through the bunched up sections, and in the open and moving sections when they appear. You don't notice the accordion effect nearly as much because you are able to defeat it by splitting or filtering.
FSMdamn, is it good!