Thx Run.
To answer some of those questions here, yes, it is rotation based but a little different than what you described.
First we have an assigned review that the reviewer has to write on. This one, I purchase the VN for the reviewer. The next is a free choice review, that the reviewer picks anything they want to review. I believe Cartagra was the free choice for this month. We also will have OELVN reviews, and poor Nohman got saddled with that one this month. Finally we have one more non-deadline reviewer who basically does what they want.