Books have been said on this issue, and the conflict and feuds about where the "hot" slots are placed in a casino are still taking place – over 60 years after slot machines were 1st placed in the casinos.
The classic rule is that the better slots were located just inside the main foyer of the casino; so that potential players walking by would be able to see actual jackpot winners … be convinced to come unto the gaming floor … play. Our reasoning is that this is no longer true.
The great majority of the mega casinos these days are jumbo complexes … you no longer can see inside from the sidewalk, so there is no longer a reason to position the ‘loose’ slot machine games in close proximity to any doors.
Another standard rule is that loose slot games are located on the major aisles in the casinos, again so that more potential gamblers could see winning jackpots and be roused to play. Notably though, 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 the slot machines 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.