About 20 years ago I was at an alumni lecture on defense policy at Princeton, and various professors complained about inefficiencies in DOD procurement. An arm went up. Sen Sarbanes was in the audience, and he told the story of Jefferson’s frigates being built in six different shipyards to satisfy Congress. That moment lowered my expectations forever.
Our procurement efforts often work quite well despite the politicization. Given peaceful conditions to ramp up construction those shipyards produced maybe the best frigates ever produced during the Age of Sail, which defeated the British in several engagements in the War of 1812
There's a plotline in For All Mankind where President Ted Kennedy has a rocket plant built in Illinois to gain support for ERA ratification and they do a bad job which makes a Saturn 5 explode. Same in the alternate universe I guess.
The size of the country... and the unpredictable political whims of specific regions meant military industry had to be spread widely to ensure broad political support... and to insulate against strikes or civil unrest that may occur in certain locales.
The Civil War and the disruptions caused by secession further highlighted the dangers of agflomerating war industries in concentrated clusters of the country.