In my pup's first season, she retrieved a wounded rooster that had a freakish tail feather. We didn't get the official measurement as my boss mounted it, but from the base of the feather (where you can feel) to the tip was 29" on the mark. It's size and the spurs indicated that it was likely a year and a half. Sometimes they just grow big for some reason or another.
When I first joined Pheasant Hunting Junkies on Facebook, I saw some huge tail feathers coming from the Utah area. At first I had all sorts of theories, but at the end of the day, there are probably just slight mutations in genetics that result in really long tail feathers.
24 5/8" is my longest. I remember harvesting that bird like it was yesterday.