Considerable research has been conducting on buck rubbing behavior. Until this research was conducted, it was not understood just how "social" rubbing behavior can be. The vast majority of rubs are meaningless. They are created and never revisited. Yet there is a particular type of rub - the signpost rub - that is highly significant. Signpost rubs are not only rerubbed in multiple years, they are also rerubbed, sniffed, and licked by most of the deer that encounter them in a given year (even does interact with signpost rubs). It is believed signpost rubs transmit important chemical messages through the population (just like scrapes, but different chemicals). Who starts a signpost rub is critical. Signpost rubs do not exist in areas without older bucks (generally at least 3 1/2, but more often mature bucks). However, once an older buck starts the signpost that season (and they are usually rerubbing a tree that shows scars of many years of being rubbed), every age buck in the population reworks the rub. That is why hunters say they saw a spike working a big rub. Yes, they do, but they did not start the rub. Older, generally mature bucks, start big rubs, but then every age buck interacts and reworks them.
Interestingly, in each region of the country, bucks prefer a different species of tree to use as a signpost rub. In Coastal South Carolina, where some of the original research was conducted, sassafras is the #1 choice for signpost rubs. In TN, eastern red cedar is the top choice. In the far north, aspen usually tops the list.
The pictures below show rub scars from repeated usage of the same trees for rubbing year after year.