Books have been said on this item, and the conflict and discourse about where the "hot" slot machines are positioned in a casino are still on-going – over 60 years after the slots were 1st placed in the casinos.
The quintessential rule is that the better one armed bandits were placed just inside the main door of the casino; so that potential players going by would be able to see jackpot winners and be enthralled to come into the casino and play. Our presumption is that this is no longer true.
Almost all of the big name casinos these days are colossal complexes and it is not possible to see inside from the sidewalk, so there is no longer a reason to have the ‘loose’ one armed bandits close-by any doorways.
An additional standard rule is that loose slot machine games are positioned on the major aisles in the casinos, again so that more potential players could see winning jackpots and be galvanized to play. Importantly though, we find that this also is no longer a universal rule.
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 slots 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 slot machine games.