Did Japan always prioritize fleet carriers, or did it also understand the need for improvised and escort carriers?
Short answerIt pursued both because the Pacific required strike carriers and convoy air cover, but it devoted too few peacetime resources to the less prestigious escort mission.
NotesJapan understood that the vast Pacific created aviation gaps even greater than the Atlantic air gap. Fleet carriers supplied offensive striking power, while escort carriers and auxiliary aviation ships were needed for convoy protection and anti-submarine warfare. The Imperial Japanese Navy had relevant First World War convoy experience and did not lack awareness of the mission. It failed to turn that knowledge into enough peacetime construction, aircraft, and trained personnel before losses and geography overwhelmed the system.