I don't know if "competency" is the right word to use.

As the OP points out in the "Assumptions", if you have a company with 5 engineers working on completely different codebases, you may make a conscious decision to not be at "level 4" code review status. Doesn't mean you are incompetent it just means you are practical.

A lot of small business operate efficiently by electing to not overly complexify their development process. So maybe instead of "competency" using a word like "sophistication" would be better