So yes, I stand corrected, Customer development would have uncovered those problems.
However, I wouldn't pay for this service when my lecturers and teaching assistants would do this for free and as they were the ones setting the exams I would prefer their advice than that of an unknown person.
As a maths/physics student (though I did various other courses too) I pored over past papers, in part as an indicator of the papers to come (though they always caught one out) and in part for practice at recapitulating proofs and writing answers under time pressure. I certainly didn't spend the course working toward the exam but it would be silly not to attempt past papers on a course that has run unchanged for previous years.
Most of our papers had example answers with them though.