The entire "aging by body conformation" system is based on body conformation just before the rut - when bucks are in peak condition. ALWAYS use the age you estimated on bucks around two weeks before the rut kicks off. In my area of western Middle TN, that would be the last week of October and the first few days of November (with a peak breeding around Nov. 15).
I talk a lot about the effects of post-rut stress on bucks. I really don't think most hunters believe me as to how detrimental it is to bucks. Many bucks die post-rut simply due to the physical stress. It is the reason - in ridge-and-hollow hardwoods - very, VERY few bucks live past 5 or 6 years old. It's not poaching. It's not other hunters killing these bucks. They die of natural causes (post-rut stress). A fully mature buck can literally lose 30% of their entire body weight during the 6 weeks of the rut. That's a 200 lb live weight buck dropping to 140 lbs in just 6 weeks. That would flat out kill most humans.
Below is a picture of an absolute tank of a 5 1/2 year-old buck. Picture was taken in late October. I will guarantee this buck goes 220-230 on the hoof (not that uncommon for a fully mature buck in the area). However, by shear chance, I killed that buck Dec. 31 - well past the local rut. By then, he was a shell of himself. He live weighed in the 170s.