> people within different occupations tend to interpret the questions differently

There are also other types of ambiguity. For example when asking: "Do you keep your room in order?" - you might answer "yes" because that's what you do, but you only do it because it has been enforced into you over time, while if you were alone and free you'd keep it messy.

Do people respond with their instinctive reaction or with their trained reaction? Which one is the right answer? Depending on that you could get a different type.

There is even more ambiguity in questions like "Do you keep your room in order". First what order for some, is chaos for others. Second some people just lie to them self or ignore the truth. For example, how would a hoarder answer that question. So the self perception could differ much from the real behaviour.

Wouldn't the manner in which a person interprets questions be part of their personality, especially if that interpretation is consistent between e.g. high school and their time in industry (as mine was)?

Indeed that might be possible. In fact there may be sub categories within the popular categories with different behaviors, e.g., a poet whose symbol is INTJ might be a different personality than an engineer with the same symbol. This would be hard to sort out because there are vastly fewer poets than engineers.

Intelligence may play a role too. Two people with the same symbols but widely different intelligence may behave differently to the point where they are identified as having different personalities. I'm speaking broadly about intelligence without necessarily believing in IQ testing.