Why carrier doctrine differed between navies

Was carrier doctrine still unsettled until the war was well underway?

Each navy had already developed a distinct doctrine suited to its own strategy and equipment, and those doctrines continued evolving during the war.

There was no universal best way to employ carriers. American doctrine emphasized concentrated Pacific strikes, while British doctrine also had to sustain air defense, anti-submarine patrols, and prolonged operations in the Mediterranean and North Atlantic. Japanese practice likewise reflected its own aircraft, carriers, strategic aims, and expected operating geography. The comparison warns against grading every navy by a single Pacific-centered model of carrier warfare.