SV tried this years ago because...some of the senior Saudi Captains would not show up for flights to "unpopular" destinations. Remember the 747 manager at the time mentioned that he couldn't fire them...so he might as well have a system in place so that they would fly their alloted 60 hours. Most popular destinations were LHR, MNL,and BKK. OK in summer were SEL & JFK, but not in winter...lousy weather. However the system was discontinued after about a year...don't remember why.