A typical juice price cycle over six weeks at my store may look like this: Week 1: $1.99; Week 2: $2.29; Week 3: $2.79; Week 4: $2.99; Week 5: $3.29; and Week 6: $3.79.
If I purchased one bottle a week over this 6-week span, I'd spend $17.14. But, if I bought six bottles the week it was at its lowest point, on sale for $1.99, I'd spend a total of just $11.94. That's more than $5 saved in just six weeks' time, without even considering coupons. Of course, I want to use my coupons at that low point, thus lowering my out-of-pocket cost even more.
If you shop cycle lows for everything you buy, you're definitely buying multiples of items when the prices are low. Remember, though, you will not buy that item again until it goes on sale weeks from now. So, while I might spend a large percentage of my budget on juice in a particular week, I won't buy juice again at all until it's on sale at a low price some time down the road.
If you followed me around the grocery store, you'd see I fill my shopping cart with an eclectic mix of items. It rarely contains all of the staples you might notice in other people's carts, because aside from fresh produce and dairy I shop strictly for items that are at their cycle lows that particular week. I usually have what looks like an unusual quantity of the same item in my cart, because I'm stocking up! I will of course use all the coupons I have for those items as I purchase them at the low price. But even if I don't have coupons for all of them, as with our juice example above, I know I won't be able to purchase these items at this low price again for almost three months, so I buy what I anticipate needing.