You don't need to switch. You can keep them loaded and won't hurt them at all.
I just tossed two G21 mags that finally wore out after about ten years of use.
So I put more stress on the magazine unloading it at the end of the day and reloading it in the morning then I would be if I just left it loaded?
Yes. I never unload my carry mags anymore. In fact I never unload my gun unless I am cleaning or using for dry practice.
that's a good point. I have always unloaded my carry gun at the end of the day. Up until now, I was even switching mags once a month for my home defense gun. Good to know that isn't necessary.