8 hour wait
As you progress through the game, they will tell you that you need to fly to another part of the world to play those levels and unlock the bonuses in order to level up. So you fly to that part of the world for an 8-hour real time wait, just to get there and play 1-2 levels before they tell you to fly somewhere else again and wait for another 8 hours. Not sure what they’re trying to achieve with this except for you to get frustrated or spend coins to “fly instantly”.