Slow-restarters and sudden late-brakers. This is really all about an oscillating wave being carried vs mean flow speed. The best part when you get the hang of it is that in many situations when you can anticipate the "slow-restart/sudden late-brake" of a dozen or so cars before you (and a couple behind you), you can act as a dampener as you strive to keep near the mean flow speed, and delightfully see the phantom jam downright evaporate in your rear view mirror.