Nothing gets me more fired up or excited than finding big rubs while scouting. And nothing, in my opinion, tells a hunter more about a buck's travel routes than these rubs. You can tell the time of day (morning or evening) that a buck is using that particular area by which side of the tree it's on and whether it's heading into or out of the bedding area.
Rub lines aren't just a row of rubs that you can stand and look in a certain direction and see one rub after another. Yes, that happens sometimes and those are the easier bucks to figure out. Normally where you find the rubs scattered over an area you have to put boots on the ground and then put the pieces of the puzzle together. A buck may give away his travel routes, but it takes time and effort to figure them out. By following the rubs to where you think he is bedding, and then doing the opposite by following them away from the bedding, you will start to get a clear picture of his habbits and how he is using the terrain.
In my opinion, rubs and rub lines are the single most important thing to pay attention to. And this is why I spend most of my time when scouting looking for rubs and the pinch points where these rubs lead to and from.