Volumes have been written on this matter, and the conflict and squabbling about where the "hot" one armed bandits are located in the casino are still there – over 60 yrs after one armed bandits were first added to the gaming floor in gambling houses.
The standard rule is that the superior slot machines were installed just inside the main doorway of the casino; so that potential gamblers going by would see actual jackpot winners … be intrigued enough to come into the casino and play. Our inclination is that this is definitely no longer the case.
The majority of the large casinos nowadays are super-colossal complexes … you can no longer see inside from the sidewalk, so there’s no longer a reason to situate the ‘loose’ slot machines near any doors.
Yet another traditional rule is that loose slots are positioned on the major aisles in the casinos, again so that more fun seekers could see winning jackpots and be galvanized to play. Importantly 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 slot 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 very 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 philosophy about where to place the loose slots.