Thanks for your confirmation, Dan.
True, but to clarify matters, one can do as I do. Once I adjust the image in Lightroom, I export the image file and remove the initially imported image from the catalog. I don't use the catalog for any purpose other than gaining access to Lightroom's image-editing tools, except as noted below, which means that I also have never learned how to use Lightroom as a catalog. (Very much like the only way my wife uses our kitchen: to walk through it as she gets from the carport to the rest of the house.)
By the way, Lightroom has a capability that Photoshop does not have -- the Book module that can be used to automatically assemble the book and send it to Blurb for printing or to create a PDF of the book. Standalone free software can be downloaded from Blurb to accomplish the same tasks, but I found Lightroom's Book module to be more powerful. That was a long time ago, so I don't remember why I felt that way. It's also possible that Blurb has improved their standalone version.