Books have been said on this subject, and the debates and discussion about where the "hot" slots are installed in the casino are still on-going – sixty yrs after slot machines were 1st placed in the casinos.
The quintessential rule is that the most favorable slots were located just inside the main doorway of the casino; so that folks walking by would see jackpot winners … be titillated to come into the casino and play. Our philosophy is that this is definitely no longer true.
Practically all of the mega casinos today are colossal complexes and you can no longer see inside from the sidewalk, so there is no longer a reason to place the ‘loose’ slot games in close proximity to any doorways.
An additional classic rule is that loose slot machine games are placed on the major aisles inside the casinos, again so that more potential players could see winning jackpots and be roused to play. 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 one armed bandits 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.