I think Konami only liked to self-publish when they were certain of good profits. Just look the X68000. Gradius was the pack-in game for the system, and Salamander plus other Konami ports came out very quickly. But they were licensed ports done by Sharp/SPS directly. However in 1993 they did a 180 and developed and self-published 5 games directly. Why just 5, and why wait until 93? Only reason I can think of is how the market was going.