The best reason I've ever heard of for knowing your rifle's 25 yd point of impact was that if you ever had reason to question your rifles zero, such as after a fall while carrying your gun, was that one could check it in the light cast by your vehicles head lights when you returned back to camp etc., and confirm whether or not your rifle was still zeroed or not.
As far as zeroing my guns at 25 yds and calling it good, never!
