Books have been set forth on this subject, and the conflict and discourse about where the "hot" slot games are placed in the casino are still taking place – more than 60 yrs after the slots were first placed in casinos.
The classic rule is that the more favourable slot machines were located just inside the main entryway of the casino; so that potential players going by would see real jackpot winners … be attracted to come unto the gambling floor … play. Our standpoint is that this is no longer true.
Almost all of the major casinos nowadays are titanic complexes … you can no longer see inside from the sidewalk, so there is no longer a reason to position the ‘loose’ one armed bandits close to any doorways.
Another standard rule is that loose slot machines are put on the major aisles inside the casinos, again so that more potential gamblers could see winning jackpots and be inspired to play. Notably though, 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 slot machine 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 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.