Only when I perceive defcon2 in my immediate vicinity. Otherwise the magazines are at capacity and rotated to not weaken the magazine spring.
I have some Argentine military mags in which the spring is so strong that I cannot fully load them without a tool. CDNN must have known they were hard to load as when I bought mine, they included the loading tool for free.
I always keep them fully topped up hoping the spring will eventually weaken a bit. I will probably die before they weaken tho.
How often do you rotate magazines?