Well several things, I prefer best practice guide 4 on reccomendation codes, secondly you do not "Fail" an installation doing a PIR it is either satisfactory/unsatisfactory, and I would agree labelling is a 2 ie needing improvement.
Periodics are not for the new electrician, even if you did your 2391 course as part of your training, you need in depth knowledge of the type of installation you are testing.
You also requires a good understanding of the regs and their relationship to installation requirements, so that you are not guessing or misunderstanding those two columns of tick boxes in the schedule of inspection and dozen or so columns in your schedule of test results.
Finally, good as these forums are, you need a process of verification in place so that any grey areas or inaccuracies can be rectified. If you are self employed, send a copy now and then of any certificate to your accrediting body