These men are always more valuable in a training role. The Japanese fell short in part because they kept their best men in until they died. The next batches tended to be completely green. Near the end, the quality of the people they sent into combat was abysmal, and the kill ratios just kept getting more and more lopsided.
Our Marines were surprised to find that the Imperial Marines they were fighting were big guys, and ‘salty’.
And as you say, like Zero, Val and Zeke pilots, they had a short shelf life.