man it is not a joke to be honest. Many time I can see it will actually stop at legend then can see a sudden speed up to force common instead to fall at legend. I always check the spot where start and can tell well will end so I know for sure it does speed up. In my 2 accounts it does the same and it is one of the reasons I do not farm them. First takes longer and I can't be that focus at work clicking and waiting for too long to grind them regardless can use Hard mode on 2v2 or insane 1v1. The fortune box drop is very low plus the mix box drop also it is affected a lot giving no box. In my accounts it is terrible. Some others are lucky and can see in matter of weeks having tons of them. Now, I use OD6 insane to grind gold and is fast for me and mix box drop it is decent and I can level up parts with them.