I've come to the conclusion that it is just as random as anything else in this game. No reward for skill, persistance or anything else. You do X some numbers of times and you have a chance of getting X for your efforts. Like winning the lottery. You can play every week for years and never win or you can buy your first ticket and retire for life. I don't agree with it, but I also don't think it is unfairly biased. It does suck that it isn't more effort based but that would reward higher level players/whales and we can't have that. Those players have already proven that they are willing to play no matter what, so no point in "unfairly" favoring them.

I don't know what level of sarcasm I am trying to convey here. I believe at least some of what I wrote.