Books have been written on this item, and the contention and arguments about where the "hot" slots are installed in the casino are still passionate – sixty yrs after slot games were first added to the gaming floor in gambling dens.
The standard rule is that the superior slot machine games were installed just inside the main foyer of the casino; so that individuals walking by would be able to see real jackpot winners … be infatuated enough to come unto the gaming floor … play. Our observation is that this is no longer true.
Practically all of the major casinos presently are titanic complexes and it is not possible to see inside from the sidewalk, so there is no longer a reason to position the ‘loose’ slot machine games close-by any doorways.
Another standard rule is that loose one armed bandits are installed on the major aisles in the casinos, again so that more people could see winning jackpots and be galvanized to play. Notably 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 the slot machines 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!
Nowadays, casinos are constantly changing their philosophy about where to place the loose slots.