I can tell you that CVSing is really, really worth it. A new one opened a few miles from me and in my mail box today were some "special" coupons good only at the new store. The coupons included 25 free 4x6 prints (I have 5 grandkids, can always print pictures), $4 off $15 purchase, a free 2 liter of soda, and $3 off any CVS brand item. Using those coupons and some of the sale things this week with ECBs, I purchased $58 worth of products, nothing I or someone in my family won't use, and paid a total of $9.40 and ended up with $14 in ECB still to spend...so CVS paid me $4.60 to take them. I did have manufacturer coupons as well which did help. There are some "tricks" to successful CVSing such as breaking your purchases into a couple different purchases. I have yet to have a clerk that gave me a hard time about this, but I know some on this board have. Also, if I get too many extra things like toothpaste (I think most of us that have CVSd for very long will never, ever have to buy toothpaste again) but I continue to get the free or almost free stuff and donate it to a homeless shelter or something like that. Read the previous CVS thread on this board and you will get some great hints on how to pair up the deals. I live by myself so don't get the huge volume that some folks do, only have 1 card but I still have a closet pretty much full of shampoo, etc which my kids "raid" when they come over.
ECBs are given on only on "specific" items and are given with your receipt. If you want to use them immediately, that is when you break up your purchases and you MUST use the ECBs that are given with the card that they were given with. So you can't give them to someone else to use or if you have more then 1 card you can't use them "between" the cards. Hope this helps. Warning, CVSing can be addicting!