&gt; Sales decline each week after payday, then recover after payday.<p>This has always been true. My dad, a career Air Force officer, would shake his head at the servicemen who ate steak after payday, and were down to eating beans by the next.<p>Heck, I read Ambrose&#x27;s book about the building of the intercontinental railroad in the 1860s, where he describes the profligate spending of the construction crews immediately after payday, and the Hell On Wheels camps that sprung up to take that money, providing hookers and blackjack.