We did use the book for formal HSing. But our idea of "formal" may be different from yours, LOL! We're pretty casual! we usually spent 30+ minutes on it per day, depending upon how much in the mood we were. Some days when he was really clicking, we went closer to an hour. But that was only if he wanted to go that long.
When we worked on the book, DS7 and I just read through the material, did the experiments, and talked about the patterns he saw in, say, the measurements of the angles when a line bisected parallel lines. We did everything orally or together on paper. There were no worksheets or "homework." He read the "Brain Teaser" problems and answered them aloud, using scratch paper as needed to get the answers.
Actually, I think it would be a fabulous book to use at the dinner table precisely because it's not a very formal book, you know? Very conversational.
I'm not sure I gave you the answer you were looking for. If I can be of more help than I have been, please post again.
I hope it works for you.