I was recently reading a test trial of the tooth wear method among like 5 or 6 nationally reputable deer biologist, they averaged only about 50% accuracy in guessing jaws of known-age deer that were submitted to them for aging. Granted they were mostly off by only a year one way or another, but considering an animal that rarely sees 5+ (I believe the stat is less than 2% of all free-ranging bucks live to 5 years old) plus or minus a year is a big deal to us hunters that want an accurate age of our harvests.