One thing to note:
Maps appear to have all of the paper items as part of the same item pool, within facet restrictions. Besides the usual rare chance of getting a new map of the next-higher level from Hoard or less (or same level for Trove) outside that process, the "guaranteed paper" could be any mix of the types available on the facet (T-maps, SoA, SoT, PS). Whether getting 3 out of 5 drops as T-maps could be a good or bad thing depending on your playstyle.