So, voidfangs happening 4 times in a row is less likely than every other combination added together. Sure. But, whatever the next four weeks bring, at the end of that 4 weeks, it will have been 1/6 * 1/6 * 1/6 * 1/6 to have happened. Let's pretend that for the 4 Fridays in December, he sells PF, Nemesis, Sunbreakers, Veil. 1/6 * 1/6 * 1/6 * 1/6. Or he sells Voidfangs, Sunbreakers, Veil, PF. 1/6 * 1/6 * 1/6 * 1/6. Veil, Veil, Sunbreakers, PF. No matter what, after 4 Fridays, there is going to be a specific order. So at the end of December, I can say, 'look how unlikely it is for him to have sold X this month' and it would seem ridiculously unlikely. You cannot use the results of 4 trials to make any accurate assessment. You need huge samples to approach the true probability. This is the Law of Large Numbers.