If you do a perfect riffle shuffle a standard deck 8 times it will return to its starting state, and people don't tend to do plan-to-palm shuffling enough to ge

If you do a perfect riffle shuffle a standard deck 8 times it will return to its starting state, and people don't tend to do plan-to-palm shuffling enough to get a good random result. If you combine the two, at least two riffles (though one or two more is significantly better) with palm-to-palms between and before, especially if the riffles are less than perfect, you tend to get a good random result (though obviously not cryptography-safe random).