Volumes have been written on this item, and the conflict and arguments about where the "hot" slot machines are located in a casino are still intense – sixty yrs after one armed bandits were 1st placed in the casinos.
The quintessential rule is that the superior slot machines were placed just inside the main door of the casino; so that potential players passing by would be able to see actual jackpot winners … be possessed to come into the casino and play. Our inclination is that this is not so anymore.
Most of the mega casinos nowadays are gigantic complexes and you no longer can see inside from the sidewalk, so there is no longer a reason to put the ‘loose’ slots in close proximity to any entrances.
Another traditional rule is that loose slot machines are installed on the major aisles in the casinos, again so that more fun seekers could see winning jackpots and be inspired to play. Notably though, we find that this also isn’t 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!
In recent times, casinos are constantly changing their perspective about where to place the loose slot machines.