Books have been set forth on this issue, and the disquiet and discussion about where the "hot" slot machines are installed in the casino are still happening – over 60 yrs after the slots were first placed in gambling dens.
The standard rule is that the superior slot machines were located just inside the main entry of the casino; so that folks walking by would be able to see real jackpot winners and be challenged to come inside … play. Our resolve is that this is no longer the case.
Most of the big name casinos nowadays are colossal complexes … you no longer can see inside from the sidewalk, so there’s no longer a reason to have the ‘loose’ slot machines close to any doors.
An additional standard rule is that loose slot machines are positioned on the major aisles inside the casinos, again so that more folks could see winning jackpots and be roused to play. Notably however, we find that this also is not 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 one armed bandits 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!
Today, casinos are constantly changing their perspective about where to place the loose slots.