Books have been set forth on this issue, and the debates and discourse about where the "hot" slots are positioned in a casino are still on-going – over 60 years after the slots were first placed in the casinos.
The traditional rule is that the better slot machines were located just inside the main entry of the casino; so that potential players passing by would be able to see actual jackpot winners and be baited to come unto the gambling floor and play. Our sneaking suspicion is that this is not so anymore.
Nearly all of the big name casinos nowadays are giant complexes … now you can’t see inside from the sidewalk, so there is no longer a reason to position the ‘loose’ slots close to any doors.
An additional classic rule is that loose slots are installed on the major aisles inside the casinos, again so that more persons could see winning jackpots and be influenced 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 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 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 perspective about where to place the loose slot games.