I practice with cheap FMJ and then refill the mags with quality +P JHP when i'm done. Around every year or so, I'll notice the JHP is looking tarnished, make sure I've got enough new JHP to reload the mags, and I'll cycle through the old stuff in a practice session. So four mags of carry JHP around once a year for me.

The same ammo's been in my go-to shotgun and rifle for years, though.