When we embarked on this Family Night Together project, and Dad decided we would use it to study the art and science of Logic as a family, Dad received some wise counsel from a veteran home school mom. 45 minutes tops she said, for the textbook. Then mix in some fun exercises.
I can report that the veteran home school mom was absolutely correct. To my great pleasure, the children are engaged and participate in the lessons from the Douglas Wilson text. But eyelids start to close and yawns proliferate after the first half hour. By the end of the first hour, the Get me outta here ! looks begin.
So, going forward, it's a half hour for the text, with Mindbender and other fun exercises for the rest of the time.