I had a very different shopping pattern than most, and, of course, we had our own dairy, beef, vegetables (fresh during the growing season, and home canned or frozen the rest of the time.) But we also had 4 kids, and it took me years before I could convince hubby to let me have chickens for eggs, and even longer before he gave in on me raising Cornish X meat birds.
Also, we raised a couple hogs most years, but not always.
I generally did one major "stock up" trip in the fall, driving 80 miles to a restaurant supply store, and stocking flour, sugar, baking cocoa, gallon jugs of molasses, etc. Essentially, a years worth of those type staples.
Then, I'd fill in with monthly shop at the local grocery.
But when the kids were all in school, I ended up going to town A LOT. And it became practical to shop loss leaders every week.
My kids swore I was the reason two separate chains went broke in our town! And it got so that the cashiers at the grocery didn't make their own list until they saw what I bought... because I only bought the *really * good deals!
The way I worked it, I only bought things like catsup, mustard, salad dressings, brown sugar, pasta... once a year! When they'd have a really good sale, I would buy a years worth. If they had a limit of 3 or whatever items (a lot less common 20 years ago), I'd just stop in more than once during the week.
I was fortunate I have a really good memory, and could essentially compare prices in my head, between the loss leader price and what I'd pay at the restaurant supply... flour was always cheaper by the 50# bag (I bought quality unbleached, not the cheapest stuff), but around the holidays, I could often find all forms of sugar significantly cheaper at the local sales. These days, I'd probably keep a small notebook.
If you are already fairly well stocked on the basics, you can save a LOT of money only buying the sales items. It's well worth it!
Summerthyme