Volumes have been stated on this topic, and the debates and discord about where the "hot" one armed bandits are placed in the casino are still happening – more than 60 yrs after slot machines were first placed in the casinos.
The quintessential rule is that the best slot machines were placed just inside the main entry of the casino; so that potential gamblers walking by would be able to see actual jackpot winners and be titillated to come unto the gambling floor and play. Our view is that this is no longer the case.
The majority of the mega casinos nowadays are colossal complexes and it is not possible to see inside from the sidewalk, so there is no longer a reason to situate the ‘loose’ slot machine games in close proximity to any entrances or exits.
Another standard rule is that loose slot games are located on the major aisles in the casinos, again so that more persons could see winning jackpots and be energized 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 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!
These days, casinos are constantly changing their perspective about where to place the loose slot machine games.