I agree, that would be of little use. In this case, however, Hammond and Scull have published
Tolkien’s notes and timelines: the movements of the
Nazgûl as they hunt
Frodo from
The Shire to the Fords of Bruinen, for instance; or the movements of
Gollum as he follows Frodo from
Moria to
the Dead Marshes. Those, I think, are outside the
realm of “opinion” and fall into the category of Tolkien’s working material. The references in such cases are obvious, “in my opinion.”
Reader’s Companion is only useful to the degree that it provides us a source for these working
materials, which are both extensive and housed at two separate sites. (Most of them, I think, are in the library at Marquette, but not all.) Tolkien worked out phases of the moon; the weather; and most importantly to discussions of
LotR, the movements and motivations of the secondary characters whose narrative we do not read in
LotR. In that sense,
Companion is a fundamentally different work from, say, Foster’s
Guide to Middle-earth, which is a mixed compendium of reference and opinion.