I went to law school and a few of us students were engineers. For our first set of essay exams, the professors all instructed us to "just answer the legal question" and not include extra analysis. After the exam, many of the engineers didn't do well because the professors *actually* wanted you to weave the whole sylabus into your answer (i.e., discuss hypotheticals that were not actually part of the question asked), not just answer the question. After that, we were fine.
This is also what I learned the hard way. In many situations the customer doesn’t say what they really want. There are a lot of reasons why. I usually have to write down a lot of hypotheticals. If X is the primary concern, we should do Y. If U is the issue, we should do V.
I wouldn't expect customers to say what they really want. They are looking for faster horses after all. But law professors? Among all professors, law professors should be the ones saying what they really want.