Has anyone figured out how the 20 cent credits work? It seems like I get a few surveys each day that offer the 20 cent minimum for trying and then it reverts to zero for trying. I wonder if they give you like five 20 cent tries each day or something like that. But yesterday, it gave me a bunch of zeroes and then a few 20 cent ones later in the day and then back to zero. I am trying to figure out the pattern but I haven't got it yet. Anyone?