I'm not really sure why Greg Jein, in coming up with numbers for all of the twelve Star Ships felt compelled to use all the numbers seen on that chart. I mean, it's not like ten of the twelve happened to be parked at Starbase 11. Other than the numbers that we did actually see or hear being used, I think the numbers should be taken with a grain of salt.
Jein interpreted the information from The Making of Star Trek
not as "there are only 12 starships like the Enterprise"
but as "there are only 12 starships" (in Starfleet).
The chart is specific as it only indicates starships, hence Jein's conclusion. I doubt these are all starships parked at Starbase 11 (then why bring starship captains in from the outside for Kirk's Court-Martial?), probably just starships that are being constructed and/or still require essential upgrades.
But what about the actual numbers? Jein's assumed NCC-1631 for the Intrepid
turns out to be "1831" in HD.
And I'm not sure whether it's really "1664" and "1697" or rather "1864" (USS Reliant!)