Diminishing return on Scroll of Deception drops

Is there such a thing? I'm mainly looking for someone affiliated with Warmane to give a definitive answer. If you get one Scroll of Deception drop, either from a RBG or raid, is it possible for another one to drop soon thereafter? I'm asking, because in all my years of playing here, I can't remember it dropping twice in one week, no matter how many raids / RBGs I've done. It' seem to pretty reliably drop once a week, though, which is why I'm asking.

It might just be bad luck, but I just want a definitive answer, so I don't have to waste my time doing random raids for nothing.

Could be just bad rng, on some chars i have 10+ scrolls, on some character it barely drops