Volumes have been stated on this issue, and the controversy and feuds about where the "hot" slot machines are placed in a casino are still bubbling – 60 yrs after the slot machines were first placed in gambling dens.
The standard rule is that the most favorable slot machine games were located just inside the main foyer of the casino; so that everyone passing by would be able to see real jackpot winners and be keen enough to come unto the gambling floor and play. Our estimation is that this is no longer the case.
Nearly all of the major casinos nowadays are enormous complexes and it is not possible to see inside from the sidewalk, so there is no longer a reason to have the ‘loose’ one armed bandits near any entrances.
An additional traditional rule is that loose slot games are put on the major aisles inside the casinos, again so that more folks could see winning jackpots and be roused 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 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!
In recent times, casinos are constantly changing their philosophy about where to place the loose one armed bandits.