Books have been set forth on this subject, and the disquiet and disharmony about where the "hot" slot machine games are installed in the casino are still passionate – over sixty years after slot games were 1st installed in gambling houses.
The classic rule is that the superior slot machines were put just inside the main entrance of the casino; so that everyone walking by would see real jackpot winners and be tempted to come inside and play. Our interpretation is that this is not so anymore.
Most of the mega casinos these days are super-colossal complexes and now you can’t see inside from the sidewalk, so there is no longer a reason to position the ‘loose’ one armed bandits close-by any doorways.
An additional traditional rule is that loose slot machines are put on the major aisles inside the casinos, again so that more folks could see winning jackpots and be galvanized to play. Interestingly 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 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!
In recent times, casinos are constantly changing their philosophy about where to place the loose one armed bandits.