I think of rubs in different ways, you have to be aware that Bucks make rubs when they are shedding velvet too those type of rubs usually appear as obvious imperfections on the tree/shrub/sapling but they don't show me any sign of an agressive type rubbing. The more aggressive the rub the more the Buck is saying on that rub whether it's a rub meant for Doe's or for other Bucks in the area, they all say something to the other deer.
When you begin to notice rubs, that's the time when you can tell where a Buck is traveling from, which direction he is heading in and depending on the area of the rub It can almost tell why he rubbed that area. one example would be a rub on the edge of a field, that to me would onle mean that he's marked his territory that's his travel corridor, a rub on the dge of a field will be seen by all deer, it doesn't mean that's where he wants to breed and it isn't warning off all other bucks because they all use the same fields, nope that type is just an indicator of territory.
A Buck makes rubs for 3 main reasons, to remove velvet, To warn other bucks away from his area and to Let Doe's know where he is and where "HE" thinks it's safe to breed.
I used to be fooled into thinking the bigger the rub the bigger the buck, That's not true in the least. I seen a Huge 8 pointer attack a 1/2 inch sappling and I saw a Spikehorn rubbing a 4" oak tree, rubbing it like he was a 14 pointer. Don't let the tree size of tree fool you into thinking you can tell the deers size because it can't. If you study every rub you see you'll begin to see things in the rubs that offer signs on the buck that did it like a Brow tine gouge, or a Rub that also had a nearby shrub that was getting damaged, that's a width type indicator, the height of the rub,,, all those things provide valuable information about the deer that made those rubs.
I focus heavily on rubs, as soon as I begin seeing a line of Rubs, that's when I start watching that area most heavily, also keep in mind a single Buck will usually use the same tree sizes when he makes a rub, if he uses 2 inch trees then most of his rubs will be on 2 inch size trees,,, that's another way to distinguish the difference between one bucks rubs and the others.
I check certain rubs every day until I can determine which ones are being freshened. here's an example, If I locate 6 rubs in a line I'll check all 6 each day for about 5 to 6 days or until I can determine which one's he's freshening daily. the 1st Rub in the line may be a territory marker, those dont get freshened OR it may be the area he feels safe to Breed in, that type will be freshened daily. Even though the Buck thinks those areas are safe to breed in it isn't his choice to decide, it's the Doe's that determine where the breeding occurs which usually isn't too far off from the Bucks intended area,,, but the Bucks rubbing efforts work to keep the other bucks at bay while he performs his Buck Duties.
I hope this helps. Good Luck to you...