Choosing an ICD-9 code (instead of just making up a diagnosis) has the advantage of populating the Problem List in the Summary Sheet, which also allows you to quickly fill your Assessment field at your next encounter.
That would be an advantage if "Hand, Foot and Mouth Disease" or "Fell, Scaped Knee" were a problem. But, they aren't. They are diagnoses on a face sheet. Personally, I don't want them in the problem list. I want problems, i.e. Asthma, Chronic otitis media, ADHD, in the problem list.
I guess I am a creature of habit, but I rarely use the ICD-9 dropdown box for a diagnosis. Probably should.