Books have been said on this matter, and the disquiet and squabbling about where the "hot" slots are positioned in a casino are still happening – over sixty years after slot machine games were 1st added to the gaming floor in casinos.
The standard rule is that the better slot machine games were installed just inside the main entryway of the casino; so that persons going by would see actual jackpot winners and be intrigued enough to come unto the gambling floor and play. Our disposition is that this is no longer true.
Practically all of the large casinos these days are titanic complexes … now you can’t see inside from the sidewalk, so there’s no longer a reason to position the ‘loose’ one armed bandits in close proximity to any doors.
Yet another standard rule is that loose slot machine games are placed on the major aisles in the casinos, again so that more people could see winning jackpots and be encouraged to play. Importantly 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 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 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!
These days, casinos are constantly changing their philosophy about where to place the loose slot machines.