I think the counter argument to this is non-perishable food and other groceries.

There is a certain brand of shelf stable non-dairy milk that my family use a lot of. The usual price is £1.50 a carton. Every few months there is a 3 for £3.00 offer. Now this is obviously a ploy to get you to buy more than you needed and also to appeal to new customers.

But I use these offers to stock up on weeks worth of the stuff. If has a shelf life of over a year so it's a no brainer. I hardly ever pay full price.