From my personal experience, and although I get owned a lot on netplay, so perhaps its not my position to say, but Shiki's AAD is widely feared. Everyone seems the know if they touch you, they're dead, so they back off as much as possible. If you time it right, in a lot of cases, they have no choice but to eat your 5000 dmg, and people don't try to spam A upon finish of the AAD if you miss, because its way to risky to get close to 7ya during his AAD, and they're usually on the other side of the screen if the AAD dis miss.
Also, while the AAD is going, and it definitely looks like its going to miss, plan ahead. Are you gonna defend right after it misses? Go for a quick grab perhaps? Stuff like that could be planned.
But if it is inevitable that you'll hit them, they're STILL one way they can get out...
If they go heat just as you touch them with AAD, they're saved, although the animation for a hit continues.