Have you had any formal training? There are a lot of schools available that would help you get calibrated for understanding your limits, most don't like to be called Long Distance hunting schools, as they aren't trying to promote the taking of animals at less than ethical conditions. One school I am familar with, uses real world scenarios, as testing means, to check effectiveness and monitor improvements to the course work. Over 1000 shooters, on ranges from 200-500+ yards, since 2005, no one has cleaned the graduation course yet. A handfull of 95% scores, zero perfect scores. All stages have time constraints, adding to the shooter stress. You might look into one of these, and get a short hunting trip worked in as a bonus.
Unfortunately, some of the TV shows, aren't showing the whole picture, there are multiple attempts and extra shooters edited out of the aired footage, leaving a false impression of what is routine. Look at most of the competitions, at UKD around 600 yards, most targets are no more than 2 MOA, which is larger than the intended impact point of a typical game animal. Those guys are certainly in the upper % of marksmen, and they aren't going 100% on those, usually a lot less under field conditions.
With trained shooters, under field conditions with hunting ammo, ethics start coming into play around the 300-400 yard mark. My Personal Ethics Zone, yours may vary, is around that number, conditions permitting. We have kept stats on this for a couple years now, and during our cull hunts, we use 300WM, in order to give every advantage. We also shoot in teams of two, which also seems to improve %. With 308, shooting alone, again, with trained shooters, not just good ole boys ( although we have a couple of those too!!!) percentages are between 60% and 70% at 400 yards, in everyday ( read as windy, with hills) conditions. Adding caliber ( 300 WM) and a partner to discuss wind with, and spot misses, gets much closer to 90%.
What part of MS are you in? I spent some time in Starkville/Columbus.