How to punish a riffle shuffle?

Question

It is common knowledge that for a deck to be considered randomly sorted, at least seven riffle shuffles should be used. However, in my experience, very few people will take the time to complete seven full riffle shuffles. Although I know there must be a systematic non-randomness in the deck, how could I use this to my advantage? If I saw a 2, 5, 6 go in the discard pile in the previous game, and I drew the same 2, should I expect a larger probability to draw a 5 than any other number? And if I draw a 5, what does that say about the 6?