Why cruiser crews expanded sharply in wartime

Why is the stated complement a peacetime figure, and how did it change in war?

Wartime demands added anti-aircraft and fully manned gun crews and required more personnel for redundancy, raising the complement from roughly 730 toward 1,000.

Wartime complements could reach 1,000 when every turret and the additional anti-aircraft weapons were manned. War also required more personnel for redundancy and prevented routine reductions in manning. In quieter periods, a cruiser could operate with only one turret manned while keeping the others supplied with shells, cleaned, and maintained. That arrangement could reduce the crew from the stated peacetime figure of roughly 730 to as few as 650, saving personnel costs.