It all depends on the tech that is performing the work. I usually won't do a head gasket until there is noticeable loose off oil on the rear or front of the head resulting in spots on the client's garage floor.
Many times when doing a head gasket, I will find things out of place that other techs caused. So, it is possible to correct problems...
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS