Angie,
The ladies are SO right that you only need one read-aloud for storytime, but I am a book lover at heart, so...
I do have my mother-in-law read one book for each genre on tape as a gift to my kiddos. She has graciously done this for years! I have also enlisted the help of my husband to read aloud some at night (if he desires to do it). Last, I have ordered books on tape from Blackstone Audio (or used the library) to do the books that way. Blackstone gives a 50% discount to homeschoolers if you call and order the audios from them. You need to tell them you're a homeschooler to get the discount.
I actually wear out with the reading aloud, so I've used these other ways of covering read-alouds creatively!
All of that to say that it is NOT necessary to do more than one read-aloud, and it's also not necessary to do more than one book for each genre of DITHR. So, you can customize the program to your comfort level with number of books.
Blessings,
Carrie