There are a couple of theories on this and ways you can get updates to the various pathcodes. If I have an update that contains unmodified objects by our company, I'll apply the update to DV or PY and test. If it passes, I'll just use the ESU application and run it against the PD pathcode. No OMW promotion of the ESU project takes place.
If I have modified objects in the ESU, I'll apply the ESU to DV, create a separate temp project for the modifed objects and retrofit the mods back in. If it's a large ESU, I'll just use the ESU app to apply to PY then advance my temp project to PY.
Grant.