Free: Contests & Raffles.
Chuck Adams says that at 20yds your group should be at no larger than 2". Then for every increase of ten yds add an inch to that. So for example your groups should look like this. My max effective range for me is the farthest distance I can put 95% of my arrows inside of a 6" circle. 10yds = 1"20yds = 2"30yds = 3"40yds = 4"50yds = 5" etc.
Are you shooting broadheads? If so, I agree with the 6"/95% rule of thumb. Whatever max range you are consistently putting broadheads inside 6", should be your max. After you get really proficient, my own recommendation is to hold shots on game to 2/3 of that range (i.e., I can make that shot consistently to 60yds, so hold shots on game inside 40) - that gives you a margin for the difference between static targets and reactive animals. My opinion, not looking for a debate.