Rebecca,
I had a very well-written answer to your question, which I lost because my computer timed out on me! So, here is a slightly more concise, not as well-written response as my prior post!
I do understand what you're saying, and I realize that time is at a premium at your house!

I think what Tansy was mentioning in her post is that both "Beyond..." and "Bigger..." do have literature study scheduled daily to go with the read-alouds in the Storytime box daily. So, you will be getting exposure to a variety of genres, study of story elements, focus on Godly character qualities, and discussion questions already if you are using either of those guides.
However, once you get to "Preparing...", "Drawn into the Heart of Reading" is recommended for the literature study portion of the day. This is because the read-alouds in "Preparing..." match the history instead. Also, once kiddos can read at the level required in "Preparing..", they are ready for deeper thinking about the books they are reading and ready to start looking at how to read with moral discernment, which are both different skills than those required when reading for pleasure.
"Drawn into the Heart of Reading" can be used without the kick-off, prereading strategies, or the projects, if you desire, however it cannot be used without the Teacher's Guide. The questions and lessons in the Teacher's Guide are what make the Student Books so much more than just a workbook. The two definitely work together.
I would also caution you against using just the Teacher's Guide or just the Student Book alone. We have had companies who have sold only one or the other and run into their customers who say they didn't like DITHR, only to find out they were only using half of the program! So, it would be advisable to use as much of the program as possible, as it's written, going at a slower pace as needed.
I understand having kiddos who love to read and who read widely. My boys have all been like that (so far). But, we do still use DITHR to help my kiddos recognize the various types of literature, to show them which story elements are most important to each genre, to help them see how the various story elements work together to make good writing, to teach them to read with moral discernment, and to take them to the next level of reading beyond reading for pleasure.
Only you can know what will work best for your family in this area. DITHR, as with any other curriculum, can be tweaked to meet your family's individual style. The structure of the program makes it more customizable than most programs by allowing you to choose your own books, the pace you read them at, the way you will wrap up a unit, and the way you will start it off. Just make sure if you tweak it, that you don't tweak so much that it is hardly DITHR anymore!
Blessings,
Carrie