Sorry. Now I do get you have noticed it. But you aren't alone. I live 1 time zone away from the west coast of the US and have seen something like six pages of spam before it was caught, which I can understand happening. Mods are human and have lives.
I have often reported one spam and found in a few minutes that it was serial spam and then just alerted the mods that it wasn't only one, more was happening. This is just a guess, that once they find the barrage, they know where and how to beat it.