I wrote about it earlier, but this story really has the most stupid level up mechanism I've ever seen in manga. Maybe it's not necessarily that different from some other bad examples, but it's exploited so heavily here. Those servants did absolutely nothing, apart from being close enough to be still counted as belonging to the party, yet they got "experience" from the fights they didn't participate in at all. Calling that experience is a travesty in itself. Of course one can't blame Second here, he's just exploiting the existing system, he didn't design it, but from a storytelling, or even worldbuilding, point of view this is such a waste.