Why Japan failed to spread veteran pilot experience

Why were Japan's initial naval aviators excellent while later replacements were much weaker?

Japan did not distribute veterans through training and new squadrons as systematically, so catastrophic losses removed concentrated experience faster than it could be regenerated.

British and American systems rotated experienced pilots into instruction, testing, and newly formed squadrons so expertise was distributed across the force. New units therefore mixed veterans with less experienced aircrew instead of concentrating either group. Japanese naval aviation kept more of its best pilots together in front-line formations, producing exceptional elite units but a brittle force-generation system. Midway and other heavy losses removed experience that had not been spread through training and replacement organizations. The contrast explains why aggregate resilience can matter more than the peak quality of a few squadrons.