I think half the time it is common sense.  If your child has had some kind of injury and is lethargic and pale, then increase is sensible.  Like the head injury, I guess if they take a knock and then they are back at play...just observation is sensible.  With our head injury I just knew something was wrong because he walked in from school and looked white and went to lie down.  They had kept him at school since lunch time and not even rung me at home... so it was instinct to just double med’s..and later I was proved right because a crisis occured.  I think as he has got older, I have gradually learned to recognize the differences between what warrant’s increase and what doesn’t...sort of trial and error.  Sometimes you get it wrong and over medicate...no one is a complete expert or psychic...erring on the safe side is sensible and atleast they live to tell the tale is my thought on that one...must dash...busy busy busy.