I'm not usually one to complain but I don't find the rewards to be that fair.
For example, in phase one I achieved every milestone except the last one for the cosmos battles, earning me 170/200 Killers "The Bird" fragments.
But for me to get him now in phase four I must complete all three of his milestones (a total of 175 cosmos battles), as two milestones will be five shards short.
In short, I have to work as hard (despite already working hard in phase one) to earn 30 shards as someone who needs to earn 50 shards, which I don't think is too fair. (Not to mention the additional SoT needed for the extra 75 battles)
I can't speak for the other birds, but anyone agree with me?