I am super suprised after opening 3 boxes for daily quest!
I still can't believe what I get from just 3 boxes, look at this xDDD
I got the worst quest (fire splinter in 2100 elo with 1 lvl cards xD) for me. I lost like 200 ELO RATING during making this quest, but it is totally worth of it!
So maybe the numbers of boxes doesn't matter at all, you just need to be lucky :D