You've got to be lucky, I guess. I zipped through ?-5 through ?-8 non-stop, one mission per.

?-7 is bloody annoying with that RNG node before the bosses. Had to run this map over 10 till it finally "clicked" and I managed to clear it.
But overall I am happy with this event - finally can go and farm some much needed manyus and bloom dragons, rather than just spending my stamina on stupid grind maps trying to earn tickets/skill/dress blooms or whatnot.

Edit: Now on the flip side - this map is insanely good for Cash Runs. Its even better than Saturday Money maps.
50 Energy nets approx 12K gold each run - It differs between 7,6 up to 14,4K from what I´ve seen. Plus you get 4 2* girls to sell.
So after 6 runs at 300 Energy, you get a LOT of money, plus a full rotation of 2* girls worth selling (another 5K gold).
Id say - once you cleared the event itself, Run this as much as you can