^While I agree in principle with the batch theory (which explains things like the gap in time between the prototypes of such ships as the Excelsior and Ambassador classes and the mass-production of said classes if we take registry numbers into account), I just can't accept this with the Oberth.
The Grissom was operating in 2285. The class ship Oberth NCC-602 must have been built even before this. The Pegasus was commissioned in 2358, and the Tsiolkovsky was commissioned in 2363. That's 73 years at the least
between these two batches, and more than 78 years at the most. Whether there were other batches between these times or not is irrelevant: Why would an old outdated design suddenly get a resurgence of newbuilds 75+ years after its introduction, when newer, more advanced designs were being manufactured at the same time? That's like the Ford Motor Company all of a sudden deciding to build Model-T's along with their new Mustangs, Focuses, and F-150s.