Hermione Aging via Time turner and an owls question

[gingerssnap1966]

No: HPFGUIDX 53554

David wrote: 
> My estimate is as follows.  At the end of POA, Hermione states that 
> dropping Divination and Muggle Studies will allow her to dispense 
> with the Time Turner.  So we may assume that she uses it to attend 
> two extra subjects.  I would suggest, with about ten subjects 
> altogether for the normal student, that would amount to between one 
> and two hours a day, with the likely estimate well towards the low 
> end of the range.

Me: 
I don't really think that she aged at all.  She certainly got an 
extra hour or so of information, but if, for example, Muggle Studies 
and Transfiguration (just pulling those out of the air-sorry if they 
don't fit canon) met from 9:00 to 10:00, she would only age one hour, 
even if she were in both of them at once.  Does that make sense?  
Certainly her body clock would lag as she has done twice as much work 
in that hour, and even "lived" it twice, so she may *feel* older. 

Now for my question, and I apologize if this has been brought up 
before:  As David stated above, dropping Muggle Studies and 
Divination will allow her to do it without a time turner.  

This brings her down to ten subjects.  Required: Transfiguration, 
Herbology, DADA, Potions, Charms, History of Magic, and Astronomy.  
Elective:  Ancient Runes, Arithmancy, and Care of Magical Creatures.

If I understand the OWLs correctly, one can get an OWL for each 
subject.  This would mean that she would be able to get 10 OWLs at 
the most.  How did Percy (in CoS) and Barty Jr. (mentioned in GoF) 
manage to get 12 OWLs?  (I think it is mentioned that Bill did too, 
but I can't find it offhand.)  Were they given time-turners or did 
they have to really juggle their schedules, or am I just 
understanding OWLs wrong? 

I vaguely remember a discussion on OWLs and NEWTs in relation to A's 
and O's, and I understood it as one per subject.  Please correct me 
if I am wrong (offline is fine if this has been overdone).

Thanks, 
Ginger