The Blackjack Shuffle Tracking method is a bit dated, and likely not very useful at land based casinos, or online. However, the method can still be used at lowered key blackjack games where the use of modern shuffling methods (such as the "Big C Cut" or automatic shuffling machines) are not in use.
The technique however should not be totally discarded as there will be times when you can find the right situation to employ this method and possibly use it to your advantage. Shuffle tracking is not a tried and true scientific method though and involves more on the player’s educated guess more than concrete facts.
The method depends on the player keeping track of where a run of high cards are through a shuffle and then correctly predicting where those cards are and cutting the deck favorably for the player. This method is hard to conquer and even the very skilled are still relying on there best guess.
Shuffle tracking doesn't work in online blackjack games, the reason for this is that the human error, or element is removed online, the cards are shuffled perfectly when shuffled by internet random number generators. You can't really see where in the deck a card lands or is discarded when the shuffling begins, so there's no way to know or guesstimate which portion of the deck the card ends up in.
Card tracking isn't as simple when the casino you're playing at uses the half cut method, also known as "The Big C". When a casino is using the half cut method the deck is cut, usually by a random player, in the middle, and then split toward the last third of the deck by the cut card, play commences until the cut card is reached, no further cards will be dealt from the shoe at this point.
The entire shoe is not played through using the above cutting method, in fact, if six decks are used, 2 entire decks may not be played at all.
Because blackjack players must use information gained by the process of elimination when using this very basic strategy, the method becomes completely useless, as the half cut method makes it virtually impossible to determine which cards remain in the deck. This method is also defenseless against most large or prominent casinos as they use automatic shuffling machines.
Blackjack players may want to keep shuffle tracking in the back of their thoughts, as you never know when you might be playing with hand shuffled cards, keep in mind as well however that shuffle tracking involves as much guess work as it does scientific fact. Shuffle tracking depends on where cards land, providing that that can be correctly predicted. That outcome depends greatly on each dealer’s personal style and habits.