Books have been said on this matter, and the debates and squabbling about where the "hot" one armed bandits are placed in the casino are still intense – 60 years after the slots were first placed in the casinos.
The classic rule is that the superior slots were installed just inside the main door of the casino; so that potential gamblers walking by would see real jackpot winners … be enthralled to come unto the gambling floor and play. Our theory is that this is no longer true.
Most of the large casinos nowadays are massive complexes … now you can’t see inside from the sidewalk, so there is no longer a reason to situate the ‘loose’ slot machines in close proximity to any entrances or exits.
Yet another traditional rule is that loose slot machines are located on the major aisles inside the casinos, again so that more potential gamblers could see winning jackpots and be roused to play. Importantly however, 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 one armed bandits 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!
Nowadays, casinos are constantly changing their perspective about where to place the loose slot games.