Books have been written on this subject, and the debates and squabbling about where the "hot" slot machines are positioned in a casino are still intense – over 60 yrs after slot machines were first placed in gambling houses.
The standard rule is that the more favourable slots were placed just inside the entrance of the casino; so that fun seekers going by would be able to see real jackpot winners … be stimulated to come inside … play. Our point of view is that this is not so anymore.
Practically all of the major casinos presently are colossal complexes … it is not possible to see inside from the sidewalk, so there is no longer a reason to situate the ‘loose’ slot machines in close proximity to any doorways.
Another classic rule is that loose slots are put on the major aisles in the casinos, again so that more fun seekers could see winning jackpots and be roused to play. Notably however, 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 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!
Today, casinos are constantly changing their perspective about where to place the loose slot machines.