I think he has a few students that he hasn't told anyone about and that he trusts as much as he can another Immortal. He asks them to help him out on occasion and gives them help when they need it. He's helped each of them plan escape routes from their current situations and hiding places, both to use if needed. A particularly trusted student might be given plans to use in certain circumstances. An example might be if the Watchers (as in the majority of the organization) have started killing Immortals again and the Watchers don't look like they can be salvaged.