User blog comment:Ixarising/High School DxD Dream Battle/@comment-112.211.199.137-20140207162046/@comment-1359322-20140207171316

You're comparing two different things, Cao Cao is a technique type, using all those big moves won't mean a thing, so Issei didn't use any huge move on Cao Cao, thus less stamina consumption.

But if he's facing Akeno, not using at big moves would be suicidal. Just getting hit by the Raikoryuu could paralyse Issei completely, and being hit bt 2 or 3 of those are definitely going to cost Issei his life. Don't forget the Raikoryuu can even eliminate the fire attack from Grendel.