Rayco Stump Grinder teeth: Average life?

[Mowingman]

What kind of average life should I expect on the Rayco "Super Teeth". I see some wear at 30hrs., but it still grinds really good. Except for freshly cut pine trees.
I know life will vary with conditions, but is there sort of an average I can expect to get before sharpening them, or throwing them away?
Thanks.

 

[Oly's Stump]

Usually I cannot go a whole day without sharpening at least some of the main cutters on the wheel. I can usually get 4-5 sharpenings before the teeth are no good. Rayco recommends discarding teeth after 1/8 inch is ground off the original new tooth.