You are right, there is no requirement to test every circuit. It is typically a spot check of a few and testing GFCI/AFCIs in some critical locations. I used an Ecos tester that did all the stuff you are talking about (polarity, ground impedance etc. Most inspectors just use a bug eye tester with a ground fault test button. My Ecos would trip GFCIs when doing the ground impedance test tho.
I did have one project, converting a WWII barracks to a medical facility where I did test every circuit. It was wire in pipe and they pulled the redundant ground. I tested the conduit integrity. Surprisingly, it was all good. (<1 ohm to the end of the run) Workmanship seemed to be better back in the 40s.
