VIDEO HERE (8:03 minutes)
*****
This is one of those things where everybody has a different opinion and all of them are probably right.
Some say to rotate them out every 6 months, some say to not bother. Some say to fill them all the way up, others (myself included) say to short stack them.
I don't rotate my magazines out on a set basis. I've got some that have been left loaded for years and fed fine when I did get around to shooting the ammo in them.
I've got a magazine for my Ruger Mk II 22LR that has been horribly abused according to some folks. It's the magazine that came with the gun when I bought it new as a birthday present to myself when I turned 25 years old. I'm 63 now.
I've left that fucker fully loaded for months on end, I've left it loaded with just a few rounds in it, I've left it unloaded. I've never pulled the follower and spring to clean or lube it, matter of fact I'm not even sure if I can.
I've used that same magazine to shoot hundreds of rounds in a single day and I've gone months without shooting the gun at all.
I have no idea whatsoever how many rounds I've put through that magazine and gun. I do know for a few years that during the winter months when it was too snowy to go to the mountains and too dry to prospect in the hills, I was buying and shooting a brick a week, 90% of it through that handgun.
I've never had a failure to feed with that magazine. Not once.
I did break down a couple months ago and bought a new magazine. I fired a box of rounds through it to make sure it fed okay, then I tossed it in my safe where it'll probably stay for the rest of my life.