Books have been said on this matter, and the controversy and ruckus about where the "hot" slot machine games are installed in the casino are still passionate – 60 yrs after slot games were first placed in casinos.
The classic rule is that the most favorable slots were located just inside the main foyer of the casino; so that casino fanatics walking by would be able to see actual jackpot winners … be attracted to come unto the gambling floor … play. Our resolution is that this is definitely no longer true.
Most of the mega casinos today are massive complexes … you no longer can see inside from the sidewalk, so there’s no longer a reason to place the ‘loose’ slot games close-by any exits.
Another traditional rule is that loose slot machines are installed on the major aisles in the casinos, again so that more folks could see winning jackpots and be encouraged to play. Importantly 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 slot 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 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 perspective about where to place the loose slots.