If you have high wear areas that get significantly deeper than most of the frets on the neck, the best practice is to replace only the most worn frets. If you repeatedly level to match the worn frets, you'll be doing full fret jobs fairly frequently – several over the life of the guitar, if you keep it for 20 or 30 years. Plus, you're going to lose fret height and make the guitar play differently until you get to the time for a re-fret.
That said, if you really go through frets fairly quickly, just bite the bullet and get a full re-fret with stainless frets.