When you see a discount on a product you often use that has a long life e.g. canned goods, buy them in bulk. Inflation on food is currently very high, so in theory – stocking up now will earn ‘interest’ at its inflationary rate by avoiding having to buy it at more costly prices in the future, although prices of course could go down.
Many costs such as car insurance attract eye watering interest that is baked into the price when you pay monthly. Clearing the balance and paying for such costs yearly mean you save a substantial amount on the cost.