The payout percentage determines the casino’s profits. Period. “PAYOUT” is the amount of cash actually dispensed vs. the amount the amount played. People who assume this can be manipulated somehow are working with some funky self-invented definition of payout. Payout is calculated by adding the “probability * payout” of each possible outcome. Note that since modern machines are all digital, this has nothing to do with the number of various symbols on the machine. The internal CPU calculates an outcome, and instructs the display to display that outcome. This makes it possible to set any outcome pattern they wish.
While it is impossible to exactly predict the payout of any machine that uses a “random number generator”, the payout will approximate the statistical expectation over time. The gambling commission does “audit the books” of individual machines to make sure that the bulk number of machines displays the expected payouts in the expected distribution. The major effect of this is: the casino can’t make appreciably more money than the payouts dictate. If they did, they would fail their audits.
And why would they bother? After all, aside from certain clearly marked banks, you rarely know the payout on any machine. It’s quite legal to set a specific machine to 92% payout, which actually DOES make more money for the casino, so why play expensive speacial-hardware tricks with a 98.9% machine, when you’re only going to make a certain return, regardless?
IMHO, the idea that there are “special times” or conditions is a classic gambler’s fairy tale that offers an illusion of advantage to the cognoscienti at the expense of the “suckers” – but on closer examination, would offer NO advantage to the house, and would complicate the machine unneccessarily, adding to the purchase price and operating cost of the machines.
Imagine what a headache this would be for a casino: if there is actually a loophole that the gambler can exploit, that machine isn’t going to have its expected payout, and may fail its audit. A hypothetical “late night jackpot” machine could be pounded at night by a knowledgeable gambler, but would be avoided by many gamblers during the day because it is visibly "dry’ or “tight”. (e.g. It’d need 200 fewer 5coin payouts to make up for each 1000coin payout – and since there are only 1440 minutes in a day, 200 “missing” payouts could be noticeable - that’s a missing jackpot every 7 minutes!)
There are several known simple, worthwhile “house tricks”, but slot players usually don’t find them very interesting, because they don’t offer the promise of a special advantage. For example, imagine three identical machines, with identical payouts. Since there are no probability tables posted (only payout tables, with no info on the relative probabilities), you could program A to offer many 2-10x payouts, but few larger payouts; B to offer more 10-20x payouts; and C to offer more 100x or higher payouts. Each would appeal to a different class of gambler or gambling superstition. The goal, after all, is to make sure that as many machines as possible get heavy play as possible. The hours of play a machine gets, the more money it makes off its relentless percentages.
Another trick: payouts are based on “max coin play”, but a big part of the calculated payouts are tied up in the “big” payoffs" which the 1-coin gambler isn’t eligible for. Therefore, despite a posted payout of 98.9%, the timid slot player may really be plugging his coins into a 75% machine by playing only one coin.
In the end, the reason I reject the “variable payout” theory is that it presumes that a casino would choose to create an additional variable (time of day, casino crowding, etc.) that is under the gambler’s control (s/he can choose when to play or not play). Why would they add expensive hardware to create what amounts to a loophole for the player, when they have plenty of ways of adding appeal (and player hours) that aren’t under the potential control of the player?
The same thing that makes this myth appealing is exactly what makes it impractical and unwise. You can pretend that your winnings would be drowned out by the 99% of suckers, but even in that case, what could the casino possibly gain for all their trouble?
[1] aka an “RNG” – actually a reasonably good pseudorandom number generator (PRNG). A real RNG would need some internal source of entropic bits, like radioactive decay. The PRNG in a slot machine uses a high precision internal clock, the precise (e.g.) millisecond a button is struck, and a mathematical algorithm with a difficult to predict output to determine the outcome of each spin.)
) I’m out to have fun with flashing lights, and minimize my losses at the slots.