Books have been said on this matter, and the contention and discourse about where the "hot" slot machines are positioned in the casino are still ongoing – sixty yrs after slot machine games were first placed in gambling houses.
The standard rule is that the most favorable one armed bandits were placed just inside the door of the casino; so that fun seekers going by would see actual jackpot winners and be inspired to come inside and play. Our theory is that this is not so anymore.
Practically all of the large casinos presently are monstrous complexes and you can no longer see inside from the sidewalk, so there is no longer a reason to situate the ‘loose’ slot machines close to any doors.
Yet another standard 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 motivated 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 very 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!
These days, casinos are constantly changing their philosophy about where to place the loose one armed bandits.