So I have never used lap books but the idea seems like a great ad on if you do unit studies. For instance, my boys have asked for a space camp and adventure camp (Indiana Jones). There are so many already made lap books it would just be a click away. Here is a link with hundreds to choose from.
There are even lap books for the Little House books. My kids are not much into worksheets but they love stuff that is content rich on a subject they are interested in.