Nope...
It's 4 weeks, then 2 weeks, then 4 weeks, then 2... and so on =p...
Whoever told you biweekly is baka =-P

At least that's what I read on the offical site =o (they have the airing dates for the whole series there, after a bit of searching around... with the final 2 eps airing on Dec25th, or christmas)

This is something the admin of Lunar-Anime posted on his forum, hope it helps you.