How Many Microns Deep or Passes Typically Done with CO2 Laser?

I am booked for a CO2 Silk Touch/Feather Touch ablative laser session for the full face, at a cost of $4000. My doctor says she will use 120 microns on her first pass, 120 microns on the second pass, and 60 microns on the third pass. This seems pretty shallow compared to how deep the laser can go, and I have moderate scarring. I am caucasian and don't tan or burn easily. To doctors who have performed or currently performing ablative CO2 Laser procedures: how many microns deep and how many passes do you typically make?