Books have been stated on this issue, and the contention and discourse about where the "hot" slots are installed in the casino are still there – over 60 years after slot games were first installed in gambling houses.
The traditional rule is that the superior one armed bandits were installed just inside the main entryway of the casino; so that individuals going by would be able to see actual jackpot winners and be smitten to come inside … play. Our feeling is that this is not so anymore.
The great majority of the mega casinos nowadays are oversized complexes … it’s no longer possible to see inside from the sidewalk, so there’s no longer a reason to place the ‘loose’ one armed bandits near to any exits.
Another standard rule is that loose slot games are located on the major aisles in the casinos, again so that more potential gamblers could see winning jackpots and be encouraged to play. Importantly 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 the 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!
These days, casinos are constantly changing their perspective about where to place the loose slots.