The program will scale the fonts to fit any of a number of booklet sizes but I prefer this size because it fits well into the pages of a standard Bible. We also use these sermon booklets for sending through the mail. When someone moves from our congregation, we send them the sermon booklets until they are established in a new congregation. Just tape them shut, flip them over, and put postage and address on the back. I use them in counseling when someone needs to study an issue more closely that I have previously covered from the pulpit.
Imagination is the only limit to their usefulness.
I have found that for some reason people are more inclined to read a booklet than a stapled stack of typed pages containing the same material. Let them continue to work hard for you. If you have ever struggled with doing a graveside service on a windy day you know how awkward it can be to hang onto your notes. A three-ring binder has always seemed awkward to me, especially in a place where there is seldom a podium. With your notes in a booklet that fits snugly into the inside cover of your Bible, this becomes a non-issue.