Books have been stated on this matter, and the debates and discussion about where the "hot" video slots are placed in the casino are still intense – over 60 yrs after slot games were 1st added to the gaming floor in the casinos.
The classic rule is that the very best slot machines were placed just inside the door of the casino; so that everyone walking by would be able to see actual jackpot winners and be titillated to come unto the gaming floor and play. Our reckoning is that this is definitely no longer true.
Practically all of the major casinos today are grand complexes … 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 near any entrances or exits.
An additional standard rule is that loose slots are positioned on the major aisles inside the casinos, again so that more folks could see winning jackpots and be galvanized to play. Notably 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!
Today, casinos are constantly changing their philosophy about where to place the loose one armed bandits.