I would think it might depend on how entries there are. I've watched the board that Cabelas in Mitchell has every year and it is 27 plus every year. If you have a smaller pool of entries it should take less to win. I.E. small town or areas that have limited amount of older birds.
There was a guy on the site that posted up the largest pheasant I've ever seen photographed, I believe he was from Canada and I think his tail was over 30, anything over 27 is pretty big.