Books have been stated on this topic, and the debates and discussion about where the "hot" slot machine games are installed in a casino are still on-going – over sixty yrs after slots were 1st installed in gambling dens.
The traditional rule is that the best slot machine games were positioned just inside the main foyer of the casino; so that people going by would be able to see real jackpot winners and be inspired to come unto the gambling floor … play. Our observation is that this is definitely no longer so.
Just about all of the large casinos presently are massive complexes and it’s no longer possible to see inside from the sidewalk, so there’s no longer a reason to put the ‘loose’ slot machines close to any entrances.
Yet another traditional rule is that loose slot machine games are put on the major aisles inside the casinos, again so that more potential players could see winning jackpots and be motivated to play. Notably 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!
Nowadays, casinos are constantly changing their perspective about where to place the loose slots.