Extreme Couponers buy in bulk.
When you buy toilet paper, you don't just buy a single roll, you buy a 4pk, 12pk, or 24pk so that you always have some on hand, or until the next time you go to the store. Extreme couponers buy in bulk so that they always have product on hand. If they run out in a couple of weeks and have to go buy some at the store, the sale might be over and they might have to pay full price! So, buy enough product to last until the next time it goes on sale. Sale cycles run every few months, so a stockpile of 3-6 months is generally sufficient.