Of course, just because someone shuffles a deck (or decks) of cards does not mean that the cards are "randomized". The methods mentioned in the two previous sections (Basic Strategy and Card Counting) assume a random order of cards. (According to some authors, a single deck of cards must be shuffled twenty to thirty times to ensure a truly random dispersion. If a Casino is using a 6 deck shoe, that's 120 to 180 shuffles!)
A beneficial (to the player) shuffle for a one deck game is executed by dividing the deck equally into 26 cards and shuffling them together a minimum of three times. This allows the cards to be sufficiently intermixed to yield a fairly random distribution. An adverse shuffle prevents the cards from mixing completely.
The simplest example is the Unbalanced Shuffle. As its name implies, the dealer breaks the deck into two unequal stacks. As an example, let's say you are playing two hands head on with the dealer and the last 10 cards in the deck are dealt. The result of the hand was that both your hands lost to the dealer primarily due to the high percentage of low value cards in the clump. Note that if you were counting, you would have bet a single unit since the deck was unfavorable. The dealer is now ready to shuffle the deck, and separates the deck into 31 cards in one stack and 21 in the other stack. The dealer shuffles the two stacks. If the shuffle is done from the bottom of each stack on up, the top ten cards of the larger stack will remain intact without mixing with any of the other cards. Those ten cards can remain in the order they were just dealt throughout the shuffle if the process of bottom to top shuffling is not altered. You are now asked to cut the deck. If you don't cut the deck, the 10 cards that were dealt last hand will be dealt as your first two hands. The result will be the same as your last and you will lose the two hands. However, if you cut the deck exactly at the end of those ten cards, you have just altered the future to your benefit. Those cards will now be placed at the bottom of the deck. Should the dealer shuffle up early, you will avoid them altogether. In addition, if you were keeping count, you would know that the deck was favorable during the first 3-4 hands since there would be an abundance of tens in the portion of the deck that will be played. You would accordingly increase you bet size to maximize your winnings.
Some dealers will unknowingly split the deck into unequal stacks. However, more often than not, they are required to split the deck into unequal stacks. If they are required to do this, they are performing the House Shuffle. The casino has trained the dealer to shuffle a particular way... on purpose! Why? In the long run, the house will benefit from this because most players will not cut any bad clumps out of play. If you have played BlackJack in a casino, how much did you pay attention to the way they shuffled? Like most people you were probably oblivious to it.
There are a number of shuffle methods, some of which have been labeled as: the "Zone Shuffle", the "Strip Shuffle", and the "Stutter Shuffle". The Zone Shuffle is particular to shoe games (multiple deck games) and is probably one of the most common shuffle methods. It is accomplished by splitting the shoe into 4 to 8 piles depending on the number of decks in the shoe. Prescribed picks from each pile are made in a very exact way with intermittent shuffles of each pair of half deck sized stacks. The net effect is a simple regrouping of the cards pretty much in the same region of the shoe as they were before, thereby preventing clumps of cards from being randomly mixed. If the dealer won 40 hands and you won 20, this trend is likely to continue until you are broke or until the unfavorable bias is removed through many shuffles.
What if the players are winning the 40 hands and the dealer only 20? If the dealer has been mentally keeping track of how many hands each side has won in the shoe, the dealer will probably do one of two things. One is to keep the shuffle the same, but 'strip' the deck. When a dealer strips a deck, he/she strips off one card at a time from the shoe letting them fall on top of one another onto the table. This action causes the order of the cards to be reversed. The main consequence is to dissipate any clumping advantages (a bunch of tens in a clump) that the players may have. The second thing the dealer may do is simply change the way they shuffle to help randomize the cards.
