I don't like the store discount cards. I think the prices after the discount are similar to stores that don't have the cards. I think it is a gimmick to make you think you are saving more money.
Also, I can do as well with a single coupon on a sale item at my usual grocery store as I can on double coupon day at the other store. You have to know your prices. I did save $65 with coupons that day, but many of those items could've been purchased at those prices elsewhere. The main point though is that I could make one trip and get some things at the usual price I would pay, some things at a lower price than I would usually pay, and a few free items.
Anyway, it is fun though time consuming at first to use coupons and find the best deals. I am to the point, too that I rarely buy anything without a discount.