mt,
me too... I was moving very slowly too in Book 1. As I had wanted them to remember every single word before I move. And everyday we revised through all the words taught so far.
But later on, I felt that maybe its not that important to remember every single word very hard before moving on. Reason being, the words are repeatedly used in the sentences later on, so they will get revision when they read. But generally they remember all the words.
Their school taught them quite well in terms of chinese reading vocab so they already know many of the words. But I really like the series, it teaches words that allow them to read a full sentence.
We generally do 1 lesson/chapter a week. I go through with them on the car 3-4 times each week.