Interesting topic. I was told that the casino does not want to give you BOTH cash winnings AND reward credits, so sometimes I remove my card, but most times I leave it in because I like receiving the reward credits to buy things. I usually go to either my favorite machines, or will wander over to one that seems to "call" me or I have a certain "feeling" about. Bottom line, due to the Random Number Generator (RNG), the machine will pay or not, regardless of whatever you put in it! Remember, it's what you take out, not what you put in!