How much is a safe amount to earn / day / month / year?

I've got access to a lot of computers that I can run Perk.TV using web browsers in a semi-busy testing center. I have read and am under the impression that browsers running perk.tv on computers do not count against the 5 devices limitation in the TOS. I haven't done it yet, but that is an option I have to get Perk more exposure and put more points in my pocket. Should I try it or just leave it alone? I can't find how much is a safe amount to earn without getting flagged even though it doesn't violate the TOS. Any ideas?

Also, in fear of having my account canceled, I cash out by using my Perk Plastik card every time it reaches $25. Is this suspicious behavior to get flagged or is it just showing that I don't have faith that the money will be there when I need it? To those that got flagged, did you do this too?