Tweaked my system a little more.

177/290 for 61% in AFL.
208/355 for 58.6% in NRL.

Both up another 1%.

This equates to POT of 18% for AFL and 13% for NRL. This is with all bets at 1.90 and no line shopping. With shopping POT goes up 2% for each.

Going to see if I can get some more seasons data.