I personally rotate my SD ammo.
Our county had an issue when deputies were involved in a high profile shootout with a cop killer and several of their patrol rifles had ammo that had bullets setback into the cases. Because no one was inspecting guns regularly or rotating old ammo out, the county instituted a rotation policy for duty ammo that continues to this day.
At work; Every year we get a fresh box for work, so I pop out the old rounds, save them, and load up fresh rounds. I have lots of spare defensive ammo with only a year in my magazines as a result, and new ammo in the gun. Since this gun is daily carry in all kinds of weather our county is very good about this.
At home; Annually I pull out the handguns that are loaded for HD/SD, examine what the rounds look like, then rotate the chambered round to the bottom of the mag (if an auto) and reload. If the round(s) look tarnished or damaged or just not right, I will rotate new ammo in to replace it.
Rifles; same routine as above since they are no longer carried daily in my vehicles. When they were carried in the cars daily, the rifle ammo got swapped out every two years.
Now, I have seen firsthand how often neglected ammo gets turned in when people retire. I’ve seen verdigris on ammo stacked in Glock mags, handgun and rifle ammo with obvious bullet setback, oil-soaked ammo, etc. all turned in by “professionals” who clearly didn’t care enough about their safety or mine to examine their stuff once in a while. Rusted rifle magazines, dirty and/or bone dry Glocks or Mini 14’s were also commonly left for me to clean, examine, lube and get ready for reissue.
If you aren’t exposing your gun/ammo to the rain/snow/heat associated with duty carry you can easily go a while without changing ammo out. But if you do carry your gun a lot, leave it in the car during summer or otherwise put some stresses on it, I think an annual (or even bi-annual) swap is probably a good idea.
Stay safe.