Have you ever investigated the evidence for such a "rule"?
Because if it's like most bro science, once such a fanciful dictum is posted on a few boards, soon thereafter it's propagated as factual info and in short order becomes bro lore.
And once something becomes bro lore, like AI/E-2 rebound, 19-Nor/prolactin elevation etc both thought and theory are thrown in the trash can, and are replaced by endless parroting which has haunted much of contemporary BB.
To that end I've no doubt some bro used a similar formula for TYPE I DAIBETICS to derive this 10 X rule.
And that's how foolish bro science can be and often is, IME!
I mean no consideration is given to the type of carbs ingested, exercise activity, BMR, the form of insulin used or its half life, or the influence of other food stuffs ALL of which effect serum glucose levels and the amount of insulin required ESPECIALLY in those who's endogenous slin production is otherwise intact.
NUTS, ABSOLUTELY NUTS!