Books have been stated on this matter, and the contention and ruckus about where the "hot" slot machine games are placed in the casino are still bubbling – 60 years after slot machines were 1st placed in gambling houses.
The classic rule is that the better slot machine games were positioned just inside the entrance of the casino; so that potential players walking by would see real jackpot winners and be stirred to come unto the gaming floor and play. Our disposition is that this is definitely no longer true.
Most of the large casinos these days are mammoth complexes and you can no longer see inside from the sidewalk, so there’s no longer a reason to put the ‘loose’ slots in close proximity to any exits.
Yet another standard rule is that loose slot games are placed on the major aisles in the casinos, again so that more potential players could see winning jackpots and be roused to play. Interestingly 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!
These days, casinos are constantly changing their perspective about where to place the loose slot machines.