Let's see if I'm able to explain.

Skeletons have no parameters included in export_descr_unit. For me it is not surprising that the faster unit beats the slow one with the same stats. The fast unit hits more times than the slow one in the same period of time.

The delay in export_descr_unit stablishes a wait time between repetition of animations (two hits for example), and it is only a small fraction of the total time. This is the reason because its effect is so small.