The brood comb I used I bought from a friend who, I think, got it from
Dadant. It has more cells per inch than the "normal" foundation. There
is supposedly some even more dense foundation available.
I do not profess to know much about accelerating the brood cycle of bees
by changing cell size, but we guessed, and guess is the operative word
here, that smaller bees might take less time to develop. If it was even
a day less, then,as shown in at a recent article, I think it was ABJ,
the faster it gets out, the less varroa. AHB has this trait and it is
given as one among many reasons for their supposed tolerance of varroa.
I do not know if the brood cycle is inviolate in bees. I doubt it. Cod
and other ground fish have been adapting and maturing earlier because of
the pressure of overfishing. Plus, we bred the bees to be larger. What
was the brood cycle when the cells were smaller and the bees were the
same? That might answer the question.
 
But, then again, it might have been the mint flavored comb I used.
Just kidding.
Be kind.
Bill Truesdell
Bath, ME