i think if you're on a hectic schedule and can only do something like once a month shopping, it would be cost effective to go to one store and stock up. it's walmart based, and what walmart does is average out the sales prices for the year to give you a general, constant low price. so it's possible to shop around and get better sales. but again, that depends if you can shop around.
i miss shopping at Sam's because of the convenience factor. we could get all our meats for the month in one trip at a reasonable price quickly, and then divide it at home. but we decided not to renew, and i've really been watching for sales at my local stores. if there's not many stores in your area to comparison shop, then it wouldn't be worth it. we have many stores within a 5 mile radius that make shopping around much more cost efficient for us.