Thoughts on teaching....If everyone in the class fails is everyone in the class stupid or is the teacher at fault? It is my opinion the teacher has failed to properly teach the lesson unless you happen to be one lucky (unlucky?) teacher.
What if a single student (let's say 10 students per class) repeatedly makes the same mistake? I claim that this is a student that needs a little more attention.
As far as to wear or not to wear...It's better to be safe than sorry, so wear it. Mistakes HAPPEN we are human, you absolutely cannot teach that away but with proper teaching you can minimize it.