Books have been written on this matter, and the controversy and discord about where the "hot" one armed bandits are placed in a casino are still ongoing – 60 yrs after slot machine games were first installed in gambling houses.
The quintessential rule is that the better slot games were positioned just inside the door of the casino; so that people passing by would see actual jackpot winners and be drawn to come unto the gambling floor and play. Our deduction is that this is no longer true.
Almost all of the major casinos these days are mammoth complexes and it is not possible to see inside from the sidewalk, so there’s no longer a reason to place the ‘loose’ slot machine games near any doorways.
Another standard rule is that loose slot machines are put on the major aisles inside the casinos, again so that more persons could see winning jackpots and be galvanized to play. However, we find that this also is no longer a universal rule.
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 machines.