[CORed]

Slot machines use random number generators. The length of time since a particular machine last hit has no effect on the probability of it hitting a jackpot. A progressive jackpot might make a machine +EV if it gets big enough. The trouble is that slot machines are a real "pig in a poke" proposition. You know what the payout is for three triple bars or whatever, but you don't know the probability of that combination coming up, so how big is big enough for a progressive jackpot is pure guesswork. Also, the really big progressive jackpots are often extremely low probability, so, even if you have a +EV in theory, you might play an entire lifetime without actually hitting one. OTOH, progressive jackpots can sometimes create a known +EV for video poker machines, where the probabilities can be calculated. I'm not surprised that the subject of the article had only losses to report. Also, I think grocery store slot machines are usually very tight anyway.