This book can be read different ways. There is nothing wrong with reading the book from the beginning to the end and then start over again.
It is more likely though that a reader feels an urge once in a while to pause reading and to spend some time meditating just one verse. Maybe after somebody has read the book a couple of times the whole symphony with all its movements and themes will be more or less present. In that case the Holy Spirit might move us to focus our attention on this theme or that theme without our knowing why.
If we do not block God's action in us, God will take complete possession of ourselves and He will become to us effectively the UNUM NECESSARIUM, the Only One Necessity. At this point we will be in complete resonance with Him, i.e. our prayer will have reached absolute simplicity, because it will be God the Father, God the Son, and God the Holy Spirit living in us.