You need multiple sets of your coupons to best maximize your extreme couponing efforts. How many of each coupon do you need? The question depends on the size of your family. The "experts" recommend one set of coupons per family member.
When you find a great sale/coupon matchup on an item, you should stock up on enough to last your family 3-6 months. Usually my four sets of coupons are sufficient for that. At times when I didn't have enough to do that, I have purchased up to 10 copies of a specific coupon online.
Why 3-6 months worth and not more? Well, you can buy 100 tubes of free toothpaste, but due to the cyclical nature of sales and coupons you'll most likely be able to find them on sale again within that time period.
My only exception to this rule is on brand new items. Often when a new item comes out the first coupons are usually a higher value than they will be in the future. You can often find some pretty good sales when items are new as well.