In the U.S, for most slot machines, every time you play the machine, each spin is an independent event that is not based on past results.
All modern slot machines contain a random number generator (RNG) which is used to control the payback percentage for each machine. When a casino orders a slot machine the manufacturer will have a list of percentage paybacks for each machine and the casino must choose one from that list. For example, a manufacturer may have 10 chips available for one machine that range from a high of 98% to as low as 85%. All of these chips have been inspected and approved by a gaming commission and the casino is free to choose whichever chip it wants for that particular brand of machine.
In almost all instances, the casino will place a higher denomination chip in a higher denomination machine. In other words, the penny machines will get the chips programmed to pay back around 87% and the $25 machines will get the chips programmed to pay back around 98%. A casino can always change the payback percentage, but in order to do that it usually must go back to the manufacturer to get a new RNG that is programmed with the new percentage. For this reason, most casinos rarely change their payback percentages unless there is a major revision in their marketing philosophy.
In regulated U.S. gaming jurisdictions the odds of getting any particular outcome on each spin of the reels remains constant and are not based on any “cycle.’ The RNG has a finite number of combinations, meaning that if the RNG has 1,000,000 possible outcomes programmed into it, then every time you push the spin button you have the same probability of getting any one of those particular outcomes. So, if one those outcomes is a jackpot, then each time you play that machine you will have a one in 1,000,000 chance of winning that jackpot. This would also apply to any other winning or losing combinations programmed into that RNG.
People will often refer to a slot machine as being “hot” because it is paying out a lot, or “cold” because it is not paying out much. However, those hot/cold “cycles” are based on random luck, applying only to what happened in the past and they won’t help you to determine what will happen in the future.
There are some machines, however, such as “must hit by” slots where this would not apply. On those machines the jackpot must hit by a certain amount, so the closer the jackpot is to that “must hit by” amount, the more likely the machine is ready to pay out.