Personally, I've always thought numbering novels was kind of dumb. Not just with ST, but with the first 10 B5 novels as well. To me, numbering only makes sense with a series of collections: Blish's Star Trek
through Star Trek 12
; ADF's Star Trek Log One
through Log Ten
; Star Trek: The New Voyages
and Star Trek: The New Voyages 2
; Strange New Worlds
through Strange New Worlds 10
, and so forth.
The only situations I can think of where numbering novels made any sense at all was with Baum's original 14 Oz
books, because they did have continuity, and the various Stratemeyer children's novel series (The Bobbsey Twins, The Hardy Boys, Nancy Drew,
&c.) (Which is to say that I have every Bobbsey Twins novel that appeared in the "purple" edition from the 1960s and 1970s, and I have earlier editions of the volumes that didn't make it into that edition, and of a few that were significantly rewritten for that edition, and of the two ["Baby May" and "Cherry Corners"] that were replaced with entirely new novels for that edition).
Incidentally, if I remember right, my copy of Della Van Hise's infamous ST novel, Killing Time,
is from the rare, uncensored, first edition. FWIW.