Seven shuffles is generally considered enough to thoroughly mix a deck of cards. This is based on a mathematical concept called "perfect shuffling," which refers to a specific type of shuffle that guarantees randomness.
However, in reality, most people don't shuffle perfectly. So, to be on the safe side, aim for at least seven shuffles, and preferably more, using a variety of shuffling techniques. This will help ensure that the cards are thoroughly mixed.
Here are some additional factors to consider:
* The type of shuffle: Some shuffles are more effective than others. For example, the riffle shuffle is generally considered more efficient than the overhand shuffle.
* The person shuffling: Experienced shufflers may achieve a good mix with fewer shuffles than beginners.
Ultimately, the number of shuffles needed depends on the specific circumstances. However, seven shuffles is a good rule of thumb to follow for most situations.