Books have been set forth on this matter, and the debates and interchanges about where the "hot" slots are located in a casino are still bubbling – over 60 yrs after slots were 1st placed in gambling dens.
The traditional rule is that the superior slot games were put just inside the entrance of the casino; so that casino fanatics going by would see jackpot winners … be keen enough to come unto the gambling floor … play. Our attitude is that this is not so anymore.
The great majority of the large casinos today are huge complexes … it’s no longer possible to see inside from the sidewalk, so there is no longer a reason to have the ‘loose’ slot machines in close proximity to any exits.
Yet another standard rule is that loose slot machines are positioned on the major aisles inside the casinos, again so that more fun seekers could see winning jackpots and be motivated 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 slot 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 perspective about where to place the loose slot machines.