Card counting is largely defeated by adding more and more decks to the shuffle. Once you get to a 6-deck shoe, it becomes very difficult to use card counting to successfully "beat the odds".
1. normal count
2. aces seen
3. face cards seen
4. <7 cards seen
Card counting is a meaneal mental task you can train yourself at, regardless of how many decks there are. It's more about how fast the cards move on the table and keeping up.