The 27,000-ton individual ceiling mattered less than the more restrictive cumulative carrier-tonnage limit. A navy could design a well-armoured carrier with a large air group within the individual limit, but building several such ships would rapidly consume its total allowance. That mattered especially to Britain and the United States because both needed carriers across widely separated theatres. British interest in protected hangars and deck-edge lifts therefore had to compete with fleet numbers and North Sea operating risks. The treaty system shaped force structure as much as individual ship design.
Notable Point · 5:25-7:12
Cumulative treaty tonnage shaped carrier fleets
The decisive treaty constraint was the total carrier allowance, which forced navies to trade individual-ship protection and capacity against the number of hulls needed worldwide.