The springs weakens by loading and unloading or working the spring. Leaving a Mag loaded will last along time. I've got 5906 mags thats been fully loaded sence 1990 and they all work just fine when I take them out and shot.
I would say load them up and forget about them. Take them out once a year and run the mag. If you don't fill safe with this just buy a couple of extra spring from wolf springs and keep them put up just a cheap insurnance.