Books have been said on this topic, and the controversy and discourse about where the "hot" slots are positioned in a casino are still raging – sixty yrs after slots were first added to the gaming floor in casinos.
The standard rule is that the most favorable slots were put just inside the main entrance of the casino; so that casino fanatics passing by would be able to see jackpot winners and be drawn to come unto the gambling floor … play. Our disposition is that this is definitely no longer the case.
The majority of the large casinos presently are oversized complexes and it’s no longer 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 traditional rule is that loose slots are located on the major aisles inside the casinos, again so that more fun seekers could see winning jackpots and be galvanized 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 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 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 one armed bandits.