Books have been written on this topic, and the bickering and squabbling about where the "hot" slots are installed in the casino are still there – over 60 years after the slots were first placed in gambling dens.
The classic rule is that the better slot machine games were put just inside the main entryway of the casino; so that individuals walking by would see actual jackpot winners and be stirred to come inside and play. Our assessment is that this is definitely no longer so.
Most of the mega casinos these days are titanic complexes … you can no longer see inside from the sidewalk, so there’s no longer a reason to position the ‘loose’ one armed bandits close-by any of the doors.
An additional traditional rule is that loose one armed bandits are placed on the major aisles inside the casinos, again so that more potential players could see winning jackpots and be encouraged to play. Importantly however, 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 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 slot machine games.