Plus, there is situational scale. If the orog is interacting with the party, or if it is seen from across the cave harassing a kitten, two different sizes would be called for.
So, I try (loosely) to categorize my small pics into portraits and everything else. The portraits are generally mid-torso and up and are roughly in scale with one another. (I should probably check my work to make sure I'm not lying.

)