The number of decks used in card games like blackjack and poker significantly impacts player strategy. A single deck allows for easier card counting and a lower house edge, enabling players to track cards and make riskier bets. Conversely, using multiple decks raises the house edge and complicates counting, prompting players to adopt more cautious strategies. Players must adjust their basic strategies to account for differences in card distribution and probabilities, while game flow affected by reshuffling and pace also changes with the number of decks.