I'm not able to log in game right now but I am 99% sure this skill has fixed rate, which means no matter what it will always be the same.
But true, most of the things related to standard attack depend on combo rate, even hinatas evansion.

You can test this very easily if you have another player or ninja exam with refine leves way above yours. Let Hinatas mystery activate and watch her get pummeled to death with standard attacks