Books have been stated on this subject, and the contention and discourse about where the "hot" slot machines are placed in a casino are still passionate – sixty yrs after slot machine games were first installed in casinos.
The classic rule is that the very best slots were installed just inside the main doorway of the casino; so that people passing by would see jackpot winners … be enthralled to come unto the gambling floor … play. Our assessment is that this is not so anymore.
Almost all of the mega casinos presently are gigantic complexes … it is not possible to see inside from the sidewalk, so there’s no longer a reason to position the ‘loose’ slot machine games close to any entrances or exits.
Another traditional rule is that loose slot machine games are put on the major aisles in the casinos, again so that more potential players could see winning jackpots and be galvanized to play. Notably however, 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 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!
Today, casinos are constantly changing their philosophy about where to place the loose slots.