I read a story a while back about someone having a 1911 given to them, that had been brought home from WWII that still had a loaded magazine with it, also from WWII. Been put up with the gun all that time. The fellow who was given the old 1911 decided to see if it would shoot with the old ammo. All 7 rounds fired without a hitch, after being loaded in a GI magazine for 60+ years. That is reliable.
I think changing out your carry ammo at short intervals got started from cops hosing off their guns with WD40 years ago. I keep an eye on my ammo. I have shot up my carry ammo and replaced it at times when I was in Law Enforcement. I bought most of my carry ammunition out of my own pocket. At about $1.50 a shot, I am not real big into wasting it. I have never ever had a round of my carry ammo fail to fire no matter how long I have had it, or carried it.
My thought on the matter. Keep a close eye on your equipment. If you get your gun wet, think you may have gotten oil or solvents, etc on your ammo. Shoot it up, and replace it. If you keep your gun year round in your vehicle, again shoot it up now and again. Ammo living in your vehicle for long periods of time is hard on it.
If your gun and ammo stay clean and dry, it will last for years. The key is staying on top of the condition of your equipment. The ammo in the wifes 686 is probably over 10 years old. The 6 rounds in the gun have probably been in it for 5 years off and on. I take the carry ammo out every now and again when the 686 goes to the range. I clean the gun, and put the carry ammo back in it again after looking it over. You can take it to the bank, It will fire all 6 times when needed.