I thiiiiink the first Saturday of the month thing evens out so it's equal every month - I often ponder it on AC weekends but never devote enough brain to accurately calculate anything.

That said, I now always work on Saturdays and its the one reliable day where housemates are home and staying up later than 10pm so I as staff struggle to be any kind of helpful in the AC process of late. If it were back to 1sts I would actually stand a chance at being available to compile the list or pick up slack instead of being the slack.