Sully, I've seen this often myself. If you want to imitate or duplicate a specific pattern then tying proportions as they do should be followed as best you can. However, fly tying, like any other art, there is always a bit of artistic license allowed. If nothing else then for the fact to compensate for a difference in water or fishing conditions (faster or slower water etc). As FAOL member Coughlin once said, "this is my version of a so-and-so pattern" clearly making it known that he admits his differs from the the classic recipe.

Then again some people tie a coon-sized version like you point out and think it looks just like a #12 Adams.