Books have been written on this issue, and the contention and discussion about where the "hot" slots are installed in the casino are still raging – more than 60 yrs after the slots were 1st placed in the casinos.
The classic rule is that the superior slot machines were placed just inside the main doorway of the casino; so that persons passing by would see actual jackpot winners and be possessed to come unto the gaming floor and play. Our inference is that this is definitely no longer true.
Practically all of the mega casinos these days are immense complexes … it’s no longer possible to see inside from the sidewalk, so there is no longer a reason to place the ‘loose’ slot machine games near to any doorways.
Another standard rule is that loose slot machine games are located on the major aisles in the casinos, again so that more persons could see winning jackpots and be encouraged to play. Importantly 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 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 very 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!
Nowadays, casinos are constantly changing their philosophy about where to place the loose slot machines.