The ladies have really done a good job of talking through this topic! I just wanted to let you know that in HOD guides, the Bible is really tied to what you are studying in history. That makes it harder to lift out and still have the same impact.
However, the "Bible Study" box in "Preparing..." will be its own study of Psalms, not linked with the history. This is because there is so much Bible study already woven into the left side of the plans (throughout our world history study) that the Psalms study is scheduled as an additional separate Bible focus for the "Preparing..." year. So, the Psalms study from "Preparing..." could be lifted out to do with everyone, but the memorization would need to be down-sized for littler ones listening in.
For what it's worth, I have enjoyed keeping the Bible study in our guides separate with my own sons to get that personal, devotional feel and that one-on-one time with each of my kiddos. Boys just don't share as easily in a group at our house as they do when they're alone with me.
Blessings,
Carrie