S.H.
Ask your grocery store, when the sales are for items.
For example, at one grocery store I go to, I asked the Butcher when the sales on meats goes on. He told me. So now I know. So I plan my menus for example, according to the in store sales. Because I asked them when the sales are. Stores, do have a routine, about when their sales start and end. Weekly. For items.
Also, personally, I make weekly menus, and I have found that to control budget/money spent, I make my grocery list according to what we already have at home on the shelves and in the freezer (so we don't waste food) and I make entrees/meals based on how many ingredients a dish takes. The more ingredients a dish requires for example, it costs more. Especially if you buy ingredients for something, that you will not usually use or if you will not likely use it again. That is a waste of money.
Or if a dish requires more exotic ingredients, that will cost more too. Or it will go to waste if you don't use it up right away.
all the best,
Susan