Shokaku and Zuikaku were laid down after treaty restraints had broken down, so treaty tonnage alone does not explain their size. Japan still had to fit the designs into available space at Yokosuka Naval Arsenal and Kawasaki's Kobe shipyard. The same yards, money, and skilled labour were also needed for other naval programs. The class therefore reveals the difference between formal freedom to build and the industrial capacity to turn doctrine into a much larger carrier.
Notable Point · 58:28-59:27
Shipyard capacity limits carrier ambition
Post-treaty freedom did not remove the physical limits of Yokosuka Naval Arsenal, Kawasaki's Kobe yard, and competing Japanese construction priorities.