I think the function would be to assess what other units are likely to do, to assess your side's vulnerabilities (i.e., what your units are doing wrong), and to improve your leadership. Figuring out what people of a given vocation are likely to do in the course of their work is certainly a core use of the vocation skills, and there's no reason that wouldn't apply to a vocation of soldiering just as it would to a vocation of marketing. Likewise, looking for shortcomings or failings of people in your own organization is a good use of a vocation skill. As for improving leadership, this sounds like a perfect fit as a complementary skill, adding your ranks in the vocation to your leadership skill.