By default, discounts provided by gifts, punch cards, or club deals can be applied multiple times to the same purchase. Suppose you have a "Buy 1, Get 1 Free" deal for coffee. If there are 2 coffees in the shopping cart, 1 of them will be free. If there are 4 coffees, 2 will be free. And so on.
From the discount configurations (Benefits > Gifts > Smart Gifts), you can limit the number of times each discount can be applied to the same purchase.
For the example above, this means that if the limit is 2 and there are 6 coffees in the cart, only 2 will be free.