You don't get promo in your scenario either. A design doc for something that's trivial will be called out in promo packet review and not given much credence. If the packet is primarily comprised of such artifacts the promo will be denied.
It depends on level. For a junior, these are great design docs because they educate other juniors about engineering, and educate senior bad-doccers about good doc writing, and show developing skill in the art of doc writing, before the engineer has the additional cognitive burden of writing about something much harder.
