Why destroyer steam pressures lagged

Why did destroyer steam conditions remain around 300 psi while larger warships moved toward 450 psi?

Destroyers already achieved the required speed and capability, while higher pressures would impose new training, maintenance, and logistics burdens without enough operational return.

Existing destroyer machinery delivered the required speed and capability, reducing the incentive for an immediate pressure increase. Higher pressures would add training and support requirements, including changes to tenders and shore facilities. Common machinery also helped sailors move between sloops and destroyers. In a war delayed beyond 1942, 450 psi plants are expected to have spread through new construction and refits. The Weapon-class discussion connects higher-pressure machinery with the support needed for operations along the long routes to the Far East.