Books have been said on this subject, and the conflict and arguments about where the "hot" slots are placed in the casino are still rampant – more than 60 years after the slot machines were 1st placed in gambling houses.
The classic rule is that the superior slot machine games were installed just inside the main entry of the casino; so that everyone walking by would see real jackpot winners … be inspired to come unto the gambling floor and play. Our perspective is that this is not so anymore.
Most of the big name casinos presently are grand complexes … it is not possible to see inside from the sidewalk, so there is no longer a reason to put the ‘loose’ slot machine games close to any doorways.
An additional traditional rule is that loose one armed bandits are positioned 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 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 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 machines.