Books have been set forth on this topic, and the debates and discourse about where the "hot" slot machines are placed in the casino are still taking place – sixty yrs after the slot machines were 1st placed in gambling dens.
The quintessential rule is that the best slots were put just inside the main door of the casino; so that potential players walking by would be able to see real jackpot winners … be intrigued enough to come unto the gaming floor and play. Our theory is that this is definitely no longer so.
Most of the large casinos these days are enormous complexes … it is not possible to see inside from the sidewalk, so there’s no longer a reason to place the ‘loose’ one armed bandits close to any entrances.
Another traditional rule is that loose slot games are put on the major aisles in the casinos, again so that more people could see winning jackpots and be inspired to play. However, we find that this also is not 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 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!
Today, casinos are constantly changing their perspective about where to place the loose slot machine games.