I use Subscribe & Save for toilet paper, paper towels, diapers & baby wipes, and random other things that I don’t need immediately (like sunscreen, washer-cleaning tablets…). Once your S&S is set up, you can add one-off items like sunscreen, have them delivered in the next month’s round of S&S at a discount, and then delete them from your S&S account. I definitely save money on the diapers. I assume I save money on the other stuff, but haven’t confirmed this since setting up the subscribe & save 3 or 4 years ago. I do (a) save the mental energy of wondering whether I have enough paper products and (b) avoid the annoyance of having to run out to get large bulky items from the store, where if you buy the value-packs at the best deal, it might not fit in the shopping cart along with the toddlers that you are forced to bring along, said toddlers also potentially being unruly by attempting to grab delicate items from their perch on the cart and whining for toys or candy.
Anyway, I really like it. The only downside is occasionally receiving too much stuff because I didn’t remember to delay a delivery until the following month when I already had plenty. It is, however, extremely easy to move a subscribed product to the next month’s delivery, adjust the frequency of delivery, and delete products altogether.
Btw, I think we use Great Northern toilet paper. I switched it to a cheaper one once, and then we were all incrementally unhappier, so I changed it back.