I know a lot of teachers who use journals as morning work on a daily basis, and generally, it becomes more of a boring routine for students instead of an instructional tool. So, I have decided to have my students do only one journal entry per week because I have found that they give me more detailed responses on the topic.
Moreover, when we do journal entries, I try to have it relate to the topic that we will be studying that week. This gives me a way to introduce the topic to the students, which will get them more involved in the unit that is upcoming.
Hope this helps, in some way.