Passed Section 1 in December. I don't think reading textbooks is the correct approach to passing these exams, using the practice exams is much more informative and provides feedback on what areas you need to study.
I learned a bunch of legal jargon for section one, which was not very useful...
My advice for section one is to know the bidding process down cold, who handles specific contract duties, the different contract types, and the order in which construction processes happen.
The reason the practice exams are so crucial is at least 30% of the exam questions are common sense and require you to reason through them. The LARE exams are designed to test your critical thinking, don't overthink studying for these exams, there will be lots of questions that require you to think on your feet and reason through them.
There is value in reading textbooks to further your understanding of Landscape Architecture, but if you are solely interested in passing the exams it is a much better use of time to take as many practice tests as possible.