Ok, from what I understood from the card drops, this thing works exactly like the voting system from the last sales. You dont have to play the game all the time to get drops, they do not drop randomly AND do not drop passively. Just like the last sales community vote would start a new vote each 8 hours, the cards drops 'reset' each 8 hours, so if a new sale day starts at 14:00 for you (like it does for me), you can get a card by starting the game at 14:00, then at 22:00, then at 6:00. The only difference is that you can get 3 cards per day instead of getting 1 card each 3 votes.