Talk:Mackerel/@comment-29621957-20170929191643/@comment-460323-20170929200707

^Minor correction; most people do the T21 into T21 skilled because the improvement level is kept post-conversion.

While improvements for both T21 and T21 skilled consume the same amount of screws, improving T21 to max requires significantly less T21 as materials as opposed to improving T21 skilled.

Ideally, you'll want to have a stash of 6~8 T21 skilled (for the occassional need in LBAS) and then convert the excess to T52 skilled (via another quest, the improvement level is kept).

It's a very cheap way to get +11AA fighters with decent stats.