Use (compression then decompression) is what wears springs. Keeping a mag full and the spring compressed does not wear them out.
Think about how many officers keep there mags full, often for an entire year before emptying them to qualify. I keep 6 loaded mags for my Sig, empty each one at least once a month if not more. After almost 20,000 rounds fired through the gun and magazines, they have yet to fail.