you guys are nuts! I dont even close the exam paper till the last second.
Depending on the exam, i normally finish 25-20 minutes early, and then i immediately turn back to the beging and do the exam again. Often i find stupid mistakes, (i.e. spelling, miscalculations, decimal points in the wrong place, etc.)
I find it hard so hard to understand, why somebody would risk losing potential marks in their final exam of their secondary-school-ing life, just so they can have an extra 20 minutes to stuff around outside.