I think what you're thinking of is when there are multiple HITs from a requester available it will grab the three highest paying HITs. However, with say C-Stats, it will log each GroupID it comes across and search for an avaialble HIT. So say you've found 12 GroupIDs, it's going to start at the top and if the first one is available, it grabs a HIT, if the second GroupID is available it will grab the HIT, if the third GroupID is available it will grab the HIT and go back to the first HIT to start again. If, however, two and three are not available, it will seach the fourth GroupID on the list, then the fifth (if both are grabbed it goes back to the first HIT again).