The time limit is tough

I don't remember exactly, but around level 80, I started running out of time even on normal difficulty. By level 120, it became common to need multiple 10-second extensions via ads just to clear stages. Maybe skilled players don't have this issue, but for someone like me, who isn't that great and plays for free, I felt I couldn't go any further. After clearing level 120 where no hidden quests remained, I quit. If the time limit were more lenient, or at least if watching ads gave a 65-second extension, I think I could have enjoyed it more.