Avoiding instant gratification is one of the most important rules of personal finance, and waiting 30 days to decide on a purchase is an excellent way to implement that rule. Quite often, after a month has passed, you’ll find that the urge to buy has passed as well and you’ll have saved yourself some money simply by waiting. If you’re on the fence about a purchase anyway, waiting a while can give you a better perspective on whether it’s truly worth the money.