Hi Donald:
Case scenarios are great!. They put the student in situations they're likely to encounter and we can evaluate their actions given a specific set of parameters. You're right in that these are time consuming. Also, without a clear grading rubric or similar tool to assure objectivity, grading can be a bit difficult. However, some topics are such that the grade is "Yep, they got it" or "nope, they missed it".
Nice contribution to the forum.
Regards, Barry