Books have been written on this topic, and the disquiet and discord about where the "hot" one armed bandits are positioned in the casino are still ongoing – over sixty yrs after slot machine games were 1st installed in the casinos.
The traditional rule is that the best slot machines were positioned just inside the entry of the casino; so that potential players walking by would be able to see real jackpot winners … be drawn to come unto the gambling floor and play. Our estimation is that this is not so anymore.
The great majority of the mega casinos these days are immense complexes … you no longer can see inside from the sidewalk, so there’s no longer a reason to situate the ‘loose’ slot machine games near to any doorways.
Yet another standard rule is that loose slots are put on the major aisles in the casinos, again so that more potential gamblers could see winning jackpots and be energized 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 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 games.