The Dango mood refresh thing is also RNG, like the Wheel Events .. That's why Dangos are important too in the latter part of your gaming life, as you level up and gather good ninjas, you will start changing line-ups and main classes depending on the situation .. For example, in battling in Space-Time where you can get matched to a player who's have great team and the only team to counter that is to change class and use your other ninjas .. or just in your daily gaming as you like to change to whatever main you want .. i for example, i'm currently using Wind main, but do also change to Lightning Mains for some instances, refreshing your mood from +nin to +atk is such a drag, sometimes i consume 80dangos or more just to get what i needed ..