Comment by watwut

Yes, because it amounts to several hours long homework. Kids are more slower then adults at reading, so this can easily amount to 10 hours of additional homework which you do on top of usual homework.

So yes, if you spent 10 hours reading a book you don't care about this week, you don't feel like reading something else. You feel like you spent awful lot of time reading already and feel like reading is something like vacuum cleaning - duty but not something you do for fun.