Steve, I used that term as a result of the original post. I've never heard it described like that although there are indeed four tracks when you step outside. Some milongueros/as lean and disassociate enough to reduce the tracks to two, someone here described it lyrically as "walking the tightrope". Try it with the right partner! I assume you mean two tracks being the path the feet of both partners take when walking in line. Track one being man's left, woman's right and track two being the one taken by the other feet. I don't think of tracks except when writing here. Oscar Casas often uses track terminology (three tracks) in videos/classes about cross system walking. It's best not to think of feet at all until much later if at all.