Lupin Wolfsbane Potion Question (Was:: Moon and Lupin)

[goodfeelinggal23]

No: HPFGUIDX 70734

MarEphraim wrote ::
<<I've read a lot of this topic off and on for a while now and 
haven't researched the archive (so forgive if this treads old ground) 
but wouldn't it be more likely (and not a Flint) if the reason for 
Lupin only changing when the moon appears is residual effect of the 
potion he's taking? He misses the dose for the evening (which is why 
Snape turns up at all) but he has been taking it on a regular basis. 
The effect is supposed to give him a measure of control, not 
necessarily preventing the transformation but allowing him a more dog-
like existence rather than werewolf-like mania. Could it not 
therefore also have a side effect of easing the transformation 
itself, making it more moon light oriented?>>

now me ::
What seems to be the bigger question to me is why did Lupin need to 
take the potion that night at all? In PoA (us, 352-3) Lupin says of 
the Wolfsbane Potion that "as long as I take it in the week preceding 
the full moon, I keep my mind when I transform . . ." So, this would 
imply (though I know it's dangerous to imply here) that it is not 
necessary for Lupin to take the Wolfsbane Potion on the night of the 
full moon. I'm sure that this has been discussed to death in pre-OOtP 
times, but anyway. I know that we aren't told how often he needs to 
take it, although it's implied that he needs or wants to take more 
than one gobletful), so why would Snape give it to him on the night 
of the full moon?? Surely Snape knows when the potion needs to be 
ingested. In my eyes, this has always been a FLINT, but I suppose JKR 
did it, as someone stated earlier, for dramatic affect and so that we 
could *see* Lupin become a werewolf. But this has always bothered me.
 
However, maybe I'm missing something. The details you all pick 
up . . . 
 
mandi :)