Books have been written on this topic, and the contention and squabbling about where the "hot" slot machines are positioned in a casino are still raging – more than sixty yrs after one armed bandits were first placed in the casinos.
The standard rule is that the better slot machine games were put just inside the door of the casino; so that potential gamblers walking by would see jackpot winners and be influenced to come inside and play. Our speculation is that this is not so anymore.
The great majority of the major casinos today are monstrous complexes and you no longer can see inside from the sidewalk, so there is no longer a reason to put the ‘loose’ slots near any entrances or exits.
Another standard rule is that loose one armed bandits are positioned on the major aisles inside the casinos, again so that more people could see winning jackpots and be influenced to play. Notably though, we find that this also is no longer a universal rule.
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 the slots 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!
Today, casinos are constantly changing their perspective about where to place the loose slot games.