The maps are groups of threes, and are rotated out each week, with a different set. And whan I reset the terrains, I always put a small map up if a big map is up, or a big map if a small map is up.
The only exceptions are the small map group which consists of 5 terrains.
Here are the current groupings, not neccessarily in the order there are rotated.
Equinox/Sfma/Mindnao
Festerma/Baltic/Frac3
Donut/Ndisles/Sfma
Trinity/Mindnao/Baltic
Ozkansas/Frac3/Ndisles
Sfma/Baltic/Ndisles/Frac3/Mindnao