Here's my understanding about rubs.
Bucks make them to mark territory, as sign to other bucks that might happen close to the area. The rubs you describe make me think you've found either the edge of a certain buck's area or one of his preferred travel routes. If they are all in a line, there's a good chance only one side of the majority of the rubs are marked. If this is the case, then you can deduce that he's moving from the direction the rubs face to the direction the rubline travels. Follow the rubline back to it's start. If there is a bedding area near the beggining of the rubline, you need to set up as close as possible in the evening. I'd guess the rubline marks his initial route when he leaves his bed in the evening. If the beggining of the rubline is near an open area, like a foodplot or a feild, I'd guess it's his prefferred route back to his bedding area. This guess would be even more firm inmy mind of the rubline ends near a bedding area. If this is the case, get as close to the end of the line in the early morning. Ifyou're lucky he'll either get the urge to ease out of his bed early one evening, or hang around a bit too long in the fields or foodplots early one morning and you'll catch him during legal shooting hours.
There's one wild card in this scenario. If the area is a prefferred area for doe family groups, it could be a place he frequents whenver he happens to be close. In this case, it's harder to guess when he'll be coming through. On the flip side, if this is the case, there's a good chance that more than one buck is frequenting the area. Keep at it. You never know when one will pop up. As we get closer the the rut, I like this second scenario because more and more bucks will start showing up. I'm amazed every year when a buck, I had no idea was in the area, shows up. As the rut gets closer,I like the first scenario less and less because once they start finding receptive does, all bets are off. The one redeeming thing about the rut is even though the buck that made those rubs might be 5 miles from there holed up with a hot doe, his competition is still likely to wander through.
Good luck. By the way, take my advice for what it's worth. I'm not a very successful buck hunter. Nowadays,I tend to let smaller bucks walk and shoot does instead of little bucks. I'm sure there are some here that could give you better advice than mine.
GH