I have found true marriage marks but once...
I think because it is impracticable to wait until an assemblage is together to mark it. How is tracking of parts achieved until that point?
In my experience yes & no - Though I've taken apart a bunch of joints in house and barn frames I've not found marks hidden in joinery.
In bridgework however I have done - While not hugely common I have found marks in the reciprocal double daps common to bridge joinery, these typically done with grease pencils not cut edges.
