The problem is, most that are still training are not ready for the intricacies of periodic inspection, it's one specific area where you absolutely cannot substitute experience of a wide range of installations and device types that could be up to 50 years old.
Anyway, code 4 ceases to exist in a few months with the introduction of the Electrical Installation Condition Report and then the fun can really begin with the coding posts!
I've been asked by the IET as a 'spinoff' to the Guidance Note 3 rewrite to look at suggested codings for the soon to be amended ESC Best Practice Guide 4 and I see many discussions ahead before agreement will be reached in that respect