Opinions/findings differ on this subject. I've seen people say you should rotate loaded mags so the springs can rest, and I've seen people who say it doesn't make any difference. I try to rotate mags at least every couple of months in the few I keep stacked full. Not saying that makes any difference what so ever, it's just what I do.
I've also seen people advocate to leave one round out of M16/AR mags to avoid feeding problems. Never seen it make a difference, but never had feeding issues I could attribute to a mag being plumb full either.
Tolerance is the virtue of a man without conviction.
The end of the world began the day it was created, and life is a sexually transmitted terminal disease.