I don't ever change my mags out. After much debate and research I have come to the conclusion that a quality magazine can stay loaded for quite some time without issue, it's the constant loading and unloading that's going to wear out mag springs if anything. I dedicate my mags for either carry or range and I have a couple just waiting that don't get used for anything until something happens to another mag.
As for ammo, it's a good idea not to continuously re-chamber the same round so I avoid that. But my carry ammo is probably a couple years old and there's no reason it should work as intended. Maybe in a few more years I'll change it out, I want to go to a heavier bullet anyway but it's what I could get.
I don't collect guns, I accumulate them.