Books have been said on this topic, and the conflict and ruckus about where the "hot" slot machines are placed in the casino are still intense – over 60 yrs after slots were first placed in gambling dens.
The quintessential rule is that the superior one armed bandits were installed just inside the entry of the casino; so that folks going by would be able to see real jackpot winners and be aroused to come unto the gambling floor … play. Our resolution is that this is definitely no longer so.
Almost all of the large casinos presently are humongous complexes … it’s no longer possible to see inside from the sidewalk, so there’s no longer a reason to place the ‘loose’ slots close-by any entrances or exits.
Another classic rule is that loose one armed bandits are put on the major aisles inside the casinos, again so that more people could see winning jackpots and be encouraged to play. Importantly 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 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 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 perspective about where to place the loose slot games.