So in other words, unlucky players going after pet food will get relics over and over again and players going after temp. military buildings will get unicorns over and over again (so no improvement for the unlucky ones).
Looks like it so far, at least for relics and pet food. In my Live city, where I must be in a test group or something, three cycles in a row with the fixed categories and three times it has been relics. No pet food yet.
But my little Beta city, which has no pets to feed, has a pet food showing right now. I can't remember for sure, but in the two previous cycles since this was noticed, I think I had relics once and another pet food?