It is interesting to find out how the slots can be set to increase or decrease the house's percentage. What I learned from a friend of my father who was a floor man in Vegas back in the 70's is that it's not always as easy as "tightening" the machines to increase house revenues. In some cases, the house will make more money in the long run by "loosening" the machines so patrons get higher payouts and more often. Word gets out, more people come in to play, and then the gross goes up, taking more to the bottom line. A lot of math and science goes into it.