Well, I am like you.
No math genious, and I only believe my 2 MarkII eyeballs.

But there is NO render quality difference due to bucket size only.
Poser does exactlky the same calculations, it just does it in smaller parts at a time.
Delivers them to screen and starts the next part, thus being less memory hungry.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!