Every unconscious patient warrants a rapid trauma assessment. Period. Even if it seems like a medical problem, a rapid trauma assessment will be putting you down the right path. Same goes for most patients with any degree of altered LOC.
Unless you know exactly what the medical problem is (ie: a diabetic man is found unconscious by his wife in bed, she says he checked his sugar earlier and was pretty low) and have absolute confidence that the patient didn't fall or injure themselves prior to or after losing consciousness, you should do a rapid trauma assessment adapted to the specific situation/patient.
Besides, it's impossible to do an focused physical assessment when you don't know what the problem is because you have nothing to focus on. \
As far as trauma patients, of course anyone with any alteration in LOC gets a rapid trauma. MVAs, falls, etc - anything that involves the entire body - should get a rapid trauma. I would say that anything involving force to the head or trunk should get a rapid trauma (example: you would want to do a rapid trauma for a kid struck hard in the chest with a baseball bat, but you may forgo a rapid trauma for a kid struck hard in the shin with a baseball bat). I would strongly consider doing a rapid trauma for any shooting or stabbing - even if the pt. believes they've only been shot in the arm, for example - because they may not be aware of other, more serious wounds.
Just a hint: your trauma patient for the national registry WILL need a rapid trauma assessment. I guarantee it. They will be sick (probably unconscious) and have a life-threatening injury (like a pneumothorax, for example), and at least one minor distracting injury (like a broken tib/fib).