Books have been written on this topic, and the bickering and discourse about where the "hot" slot machines are installed in the casino are still ongoing – sixty yrs after slots were first added to the gaming floor in casinos.
The traditional rule is that the more favourable slot machines were positioned just inside the main entrance of the casino; so that folks walking by would be able to see actual jackpot winners … be keen enough to come unto the gambling floor and play. Our speculation is that this is no longer true.
Most of the major casinos nowadays are massive complexes … you no longer can see inside from the sidewalk, so there’s no longer a reason to situate the ‘loose’ slot machine games close to any doorways.
Yet another traditional rule is that loose one armed bandits are placed on the major aisles in the casinos, again so that more potential gamblers could see winning jackpots and be roused to play. Importantly however, we find that this also isn’t a universal rule any more.
What casinos found over the years is that people walking down the busy aisles were frequently on the way to somewhere else. If they played slot machine games at all, they would simply put in their loose change because they happened to be walking by. Win or lose, they would very often not stop to keep playing. And the last thing a casino wants is for someone to win a jackpot by playing only a few coins and then not stay to put it all back in!
Today, casinos are constantly changing their philosophy about where to place the loose slots.