Construction time for the first-flight Harringtons
I very deliberately based the construction of the first Harringtons on the model of the Dreadnought, and their building times should not be taken as representative of building times in general. Indeed, I'm pretty sure that I never said they should be.
In order to get those ships completed in the time they did, the GSN diverted all sorts of components from other ships in the building queue: fusion plants, compensators, impeller nodes, armor The list is very long, because the ships were given the equivalent of ultimate omigod priority. They could never sustain a building rate that high, because they only managed to do it delaying the ships (all old-style SDs) from which the components were diverted for more months than they saved on the construction of the first-flight Harringtons. From where they sat, this was an entirely reasonable thing to do, and their desire to get the name ship launched by a certain date also contributed to their willingness to do this. As I said, I deliberately took the Dreadnought for a model, and if you go back and look at her case, the Brits only managed to set the record they did for her construction by diverting main turrets from two other ships (Nelson and Agamemnon) to her. With the result that both of those ships (late pre-dreadnoughts or semi-dreadnoughts) were badly delayed and even more obsolescent when they finally commissioned than they would otherwise have been. BTW, "old-style" SDs may be thought of as "predreadnoughts." Because of the differences in the missile environment, SD(P)s have far better point defense built into them, in addition to the increase in firepower. So they are bigger, stronger, tougher, much more heavily armed, and even (with the new Manty compensators) faster than SDs. It was argued before Jutland that one of the German predreadnought battlesquadrons might last 10 minutes up against more modern ships. At Jutland, they did somewhat better than that but they didn't manage to inflict any damage, either. Old-style SDs would find themselves very much in that position up against an SD(P). Most navies who operate both types are currently assessing 1 SD(P) as being worth at least 3 and more probably 4 of the older types.