the law of 3's
Most grinders have a number of teeth divisible by 3's.
Take the outermost set of three and move them back to the middle when beat.
Move the middles to the front and so forth.
Once the third or last set is beat then either sharpen or replace.
For the record I run CEI 800 SERIES teeth. I have done easily 50 stumps of varying widths here in the Northeast(rocky soil form glaciers) and have not sharpened yet!!!
(knock on wood)