Books have been stated on this matter, and the debates and disagreement about where the "hot" slot machines are located in a casino are still intense – sixty years after one armed bandits were 1st placed in gambling dens.
The traditional rule is that the better slot machine games were placed just inside the door of the casino; so that potential players walking by would see actual jackpot winners … be impressed enough to come inside … play. Our perspective is that this is no longer true.
Almost all of the major casinos these days are titanic complexes … you can no longer see inside from the sidewalk, so there’s no longer a reason to put the ‘loose’ slot machines near to any doors.
An additional traditional rule is that loose slots are located on the major aisles inside the casinos, again so that more fun seekers could see winning jackpots and be inspired to play. 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 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 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 slot games.