Not totally true: for such case if you have a nasty bug and you are quite sure to have fix the problem, then you can ask Apple review team for an expedite review. There is an online form to fill up, and you are good to go. I know at least 2 developers that had to use it and their update was approved in less than 4 hours. Obviously it is not for abuse and only for critical issue but the idea that it will take a standard full review time for Apple to approve an emergency bug fix is totall untrue.