Volumes have been stated on this topic, and the debates and disharmony about where the "hot" slot machine games are located in a casino are still there – more than 60 years after slot machine games were 1st placed in the casinos.
The traditional rule is that the more favourable slot machines were placed just inside the main entryway of the casino; so that potential gamblers going by would see real jackpot winners and be drawn to come unto the gaming floor and play. Our frame of mind is that this is definitely no longer so.
Nearly all of the large casinos these days are giant complexes and it’s no longer possible to see inside from the sidewalk, so there is no longer a reason to have the ‘loose’ slots close to any entrances or exits.
An additional standard rule is that loose slot machines are put on the major aisles in the casinos, again so that more potential players could see winning jackpots and be roused to play. Notably however, 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!
In recent times, casinos are constantly changing their philosophy about where to place the loose slot machines.