Books have been said on this matter, and the contention and interchanges about where the "hot" slot machines are located in the casino are still ongoing – more than sixty years after slots were first added to the gaming floor in gambling houses.
The standard rule is that the better slot machine games were put just inside the main foyer of the casino; so that fun seekers walking by would see jackpot winners and be aroused to come inside … play. Our philosophy is that this is definitely no longer so.
Just about all of the large casinos today are mammoth complexes … now you can’t see inside from the sidewalk, so there’s no longer a reason to position the ‘loose’ slots in close proximity to any doors.
Another standard rule is that loose one armed bandits are put on the major aisles inside the casinos, again so that more potential gamblers could see winning jackpots and be motivated to play. Importantly though, 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 the slot machines 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!
These days, casinos are constantly changing their philosophy about where to place the loose one armed bandits.