Books have been stated on this issue, and the conflict and discord about where the "hot" video slots are placed in a casino are still ongoing – over 60 yrs after the slot machines were first added to the gaming floor in gambling dens.
The quintessential rule is that the superior slot machine games were put just inside the main foyer of the casino; so that individuals walking by would see jackpot winners … be tempted to come unto the gaming floor … play. Our assessment is that this is definitely no longer so.
Practically all of the major casinos presently are gigantic complexes … you can no longer see inside from the sidewalk, so there is no longer a reason to put the ‘loose’ one armed bandits close to any doorways.
Yet another standard rule is that loose slot games are located on the major aisles inside the casinos, again so that more persons could see winning jackpots and be roused 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 machine 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 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 perspective about where to place the loose slots.