There are lots of kinds of goals. Reading a specific amount per day is a good one for people who want to get into the habit. But a goal can be anything, I have a goal to DNF books without guilt if I'm not enjoying them. Even when I'm trying to learn something new, I know that there are many books on the topic and if I find one that I'm struggling to finish, I'm happy to quit it and find another that may be better for me.