Volumes have been set forth on this topic, and the controversy and face-offs about where the "hot" one armed bandits are installed in the casino are still ongoing – more than sixty yrs after slot machines were first added to the gaming floor in casinos.
The quintessential rule is that the best slot games were located just inside the main door of the casino; so that fun seekers passing by would see actual jackpot winners … be tempted to come into the casino … play. Our inclination is that this is definitely no longer so.
Practically all of the mega casinos today are jumbo complexes and it’s no longer possible to see inside from the sidewalk, so there is no longer a reason to have the ‘loose’ one armed bandits close to any entrances.
Another classic rule is that loose slots are located on the major aisles in the casinos, again so that more persons could see winning jackpots and be motivated to play. Notably however, 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 slots 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 slots.