I think a 50-yard zero is probably not optimal. Consider the ballistics of the bullet you're using. For example, the Hornady 500 gr 458 RN at 2050 fps gives these results, rounded to the nearest whole inch (who cares closer than that?):

25 0
50 +1
75 +1
100 0
125 -1

Based on these numbers, my 458 Win Mag is sighted in one inch high at 50 yards. I'm confident shooting it to more than 100 yards.

Many people complain that predictive ballistics are useless, but I disagree. Calculated trajectories often fail to coincide with shots fired for "ground truthing," but not by that terribly much. The predicted trajectory gives you a place to start, to be followed by many shots fired in practice and confirmation.