Fun fact: by being able to access the payout statistics menu and knowing the machine's installation date it was easy to know which machines would be "hot". I have witnessed machines that paid out poorly for a couple years (+ a few million USD) but would hit regular jackpots near the end of their expected lifecycle.
I'm dubious that there is a per-machine fixed sum over a fixed time like this. Apart from the "progressive" machines that have a jackpot shared across a network of machines, I'm pretty sure that the payout percentage is just a statistical prediction, and that by law each result has to be independent of all previous payouts. Do you have a reference that you could point to that would confirm your understanding? The sources I've found say that each play is random: http://www.vegasslotsonline.com/faq/#random. You might be right, but I wouldn't want you or someone else to rely on this information if it's a myth.