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I mentioned this in another thread somewhere recently, but in statistical tests of the randomness of physical shuffles when only "riffle shuffles" (or whatever the proper name is) are used there is an optimum number of shuffles, any more or less and the distributions become less random. I believe the number was 5 or 7.
I also believe that the same studies resulted in the procedure that most if not all casinos require for poker, single deck and two deck blackjack, which is that there be a "wash" before the riffle shuffles. The wash was found to result in better randomness.
DS might have done some consulting in this area?
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Copernicus, here are two good links for you about random card shuffling.
How Many Times to Shuffle
Perci Diaconis reference in Wikpedia