If 3 planes hit the same donut maker one after the other it only counts as one hit. If you get free booster minutes the amount of challenges does be popping up and delaying play time. By the time you exit all and ready to play at least 5 minutes from your 15 minutes up. Game sticks when you can beat hard level or you don't get any play in needed areas. If you design this game to rob players their money shame on you.