Probably how they used to keep all their Tigers, but superceded by the bigger open enlosures- but these are still being used owing to the number of Tigers they hold.
I don't know sorry. I would like to think they are rotated but I actually doubt it. I'm not sure if there's even any passageway running behind to allow this. (These cages are situated between the big glass-fronted enclosure for orange tigers and the island for white tigers; there would need to be a passageway along the length of the rear of these cages to allow any tiger to be moved to the big enclosures, unless they were crated up and moved manually).
More than likely the Whites have the large enclosures permanently, and the normals get the cramped ones permanently too. though I think in this photo there's a normal and a white sharing.