Carole Franki I think it certainly is! It might be even quite practical to devote an entire lesson/ lecture to explain how language users choose to be indirect or prefer euphemism to achieve certain ends. In literary courses, there is a fair opportunity to encounter euphemism and circumlocution and therefore, these courses may be a suitable venue. If that‘s impossible, then it is useful to let learners know about how circumlocution works. You can always drop a hint here and there and get the learners intrigued.
The purpose of the class is a key consideration. Does the topic serve that purpose effectively?
In a military environment such as the one you describe, I believe circumlocution can be fruitful enrichment for strong students, but probably not a focal point for the whole class. Especially for students who are not studying in their first language, more essential topics could offer more value.
That said, in other contexts such as academic or business speaking, circumlocution can be an excellent element of course material. It can certainly prove to be a valuable skill in these fields.
In short, alignment to the purpose of the course would be my general guideline, with adjustments for individual class and student needs. Best practice is an excellent departure point, but the individual context is the ultimate testing ground :).
Definitely, it is useful to train EFL students on circumlocution in speaking. Here is a study that could provide more insights.
Alaraj, M. M. (2017). EFL speaking acquisition: Identifying problems, suggesting learning strategies and examining their effect on students' speaking fluency. The International Journal of Social Sciences and Humanities Invention. https://doi.org/10.18535/ijsshi/v4i1.05
As a DLI alumna myself, circumlocution was key for effective communication for me both in the training environment and in later years when using my secondary languages. However, it wasn't a skill that was necessarily taught in lessons, per se. Rather, if we got stuck, the teacher would ask us if we could say it a different way. Circumlocution is a useful skill no matter the language or the speaker's level of proficiency. I have even used it with my own children in the process of learning their native language; sometimes they don't know how to say something so we talk around it until they feel the subject has been expressed and understood. It is also a useful skill for military (or others) who may need to broach sensitive topics, particularly in cultures other than their own, where a direct approach may be offensive or ineffective.