Books have been stated on this topic, and the conflict and interchanges about where the "hot" slot games are placed in the casino are still on-going – 60 years after one armed bandits were 1st placed in casinos.
The traditional rule is that the best slots were located just inside the main foyer of the casino; so that people going by would see real jackpot winners and be impressed enough to come inside … play. Our conclusion is that this is no longer the case.
Almost all of the large casinos nowadays are jumbo complexes and you no longer can see inside from the sidewalk, so there is no longer a reason to situate the ‘loose’ one armed bandits near to any of the doors.
Another standard rule is that loose slot machines are placed on the major aisles in the casinos, again so that more persons could see winning jackpots and be galvanized to play. Notably however, 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 slots 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!
Today, casinos are constantly changing their perspective about where to place the loose slot machines.