Why Japanese carrier aircrew losses were operational

Were Japan's severe carrier-aircrew losses caused more by ship design or by operating practice?

Primarily by operational doctrine, including how the carrier forces were grouped and the combat situations in which they were committed.

The question contrasts American recovery of veteran crews from lost carriers with Japan's heavier loss of experienced aviators. The explanation lies in the realities of the battles and the way Japanese carrier forces were grouped and employed. Hull design cannot by itself explain whether trained aircrew are exposed, recovered, or repeatedly committed under unfavorable conditions. Operational doctrine and combat employment magnified the human cost of carrier losses.