I've had four mags for my duty weapon loaded from one requal to the next, which is a six month span, with no ill effects. All the mags get unloaded and reloaded/used on this basis, and have been for almost ten years. Never a MF.
I used different mags in the same weapon for IDPA etc, as they take a much larger amount of use/abuse, and still haven't had a problem with function with my comp mags either.
I would say that an OEM magazine or a high quality aftermarket will work if loaded for long periods of time, at least that has been my experience.