Keep something in-mind, while carrying antlers, bucks will be actively rubbing from the time they shed they're velvet, to the time they drop they're antlers. Any area with concentrated rubs (more than say 10 in a 50 yard area), is defineatley worth studying. If they're is multiple scrapes in the same area, that's even better.

With that being said, just because you see a rub-line doesn't mean that a buck is going to be travelling in that area like it's a high-way, everyday. Most bucks have litterally thousands of rubs in they're home areas, with certain spots they seem to prefer to really go nut's in. Mostly, these will be areas where does travel, and where the buck wants to establish sign-posts alerting other deer to his presence.

Best method I've used to kill bucks on rub lines is to find the freshest possible sign, set-up, and hunt immediately. If you find a spot that was recently rubbed and scrapped up good (FRESH-FRESH-FRESH), you have to take advantage of the bucks activitly in that area right then, and sometimes you can catch him coming back through over a several day period. IMO, this is due to a doe that may be coming-in, or an area he knows holds lot's of does (which means during the rut he will be searching in the general area).

Keep one thing in-mind as well. Typically any area that is completely shredded is an area the buck feels most comfortable useing. Typically, the wind will be in his favor getting into and out of such areas. Make sure you have the wind, because he get's one whiff and game's over in that area. You may need to figure out a spot where he's coming and going from the "Core" area and surprise attack him there, where you can have an advantage with the wind. Good luck eh!