Why are there non work-related items in OPTO?

The items in OPTO are linked to some specific personality traits and the behaviour is derived from these. Therefore, the OPTO questions are not related to “what you do” but more “who you are” on a slightly more general level - i.e. your personality.

Thus, the areas that OPTO measures (Dimensions and Aspects) can be generalized to many different situations. That’s pretty much how all Big Five tests are built up, and you can read more about the structure of the OPTO in the documentation manual. All items are validated against the scale they measure, so we know for certain that the specific questions are related to the personality traits we would like to measure.

That validation can also be found in the documentation manual (e.g. the studies about Item-Total Correlations or Alpha Reliability). It is one of the areas where a comprehensive personality test such as OPTO differs from behavioural tests.