This. I'm 40 and getting my MBA part time while working and being a parent and I can tell you even as an adult: when you hand me a 20 page case study I will read it but I'm going to be swearing under my breath the whole time.
In today's day and age reading anything long is asking a lot.
My daughter (10) routinely reads 400+ page books meant for kids older than her, but give her a 200 page book in class and she struggles with it even though it's a lower reading level because it is a chore.