My theory is this. If you can afford it just keep stacking it up as long as you have space and can keep mice out of it. It doesn't go bad and it isn't like somebody is going to invent something better and make standard toilet paper obsolete. Of course my DH likes to argue this point. He tells me someday they will invent something better that all our friends will be talking about how cool it is and he will have to tell them we are still using the old fashioned stuff and they will make fun o us. But seriously - you will eventually use it - so I stock up when it gets cheap.