[mrob]

>The point of the exercise is to demonstrate the student's understanding of the material, not their WPM.

Testing for understanding requires the fastest WPM possible. Regardless of the method used, students don't all write at the same speed. To minimize the influence of this variance, they need to use the fastest writing technique possible. If a fast writer spends 30 minutes writing in a two hour test, and a slow writer needs a full hour, the fast writer gets 50% more thinking time. But if you double both their writing speeds, the fast writer's advantage drops to 17%.

The faster the writing technique people are allowed to use, the better your test can identify poor understanding.