Ex Inspection plan – is it a must have?

Normally one wins the tender of a site Ex inspection (E.g visual) and goes to site and does his job. Is it ok that way?
What about questionmark: assembly or manufacturing? Without prior assessment no chance to give the correct answer to all above and it might lead to non compliance even if found all fine.
We just had a case, where we were contracted to be the owner’s engineer in the name of company (well known chemical factory):

1. Ex inspector found all correct
2. Many systems (functional units) were assembled, renewed, modified, moved to a new installation place
3. Used the same Ex label as before

We recommended to define all steps again, because that way Ex inspector accepted sg incorrect to be correct under a company logo which not even existed anymore… there some became to be new manufacturers in many ways…

Many were shocked to take the responsibility of ownership after their job was done.
Keep up good work!