Books have been said on this subject, and the debates and discord about where the "hot" slots are located in a casino are still rampant – 60 years after one armed bandits were first installed in casinos.
The quintessential rule is that the very best slots were positioned just inside the main entryway of the casino; so that casino fanatics passing by would see real jackpot winners and be infatuated enough to come unto the gambling floor and play. Our disposition is that this is definitely no longer true.
The great majority of the major casinos presently are titanic complexes and it is not possible to see inside from the sidewalk, so there’s no longer a reason to situate the ‘loose’ slots near to any doorways.
Yet another standard rule is that loose slot machines are put on the major aisles in the casinos, again so that more potential players could see winning jackpots and be energized to play. 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 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 slot machines.