Ok but you can reset a regular wrist watch to 12:00 and have it count up to 35 minutes for each section. I don't see how this would be any different. It seems kind of crazy.
Also, in the grader, input your original answer into the grader. Then, if during your blind review you changed your answer, click on the actual number in the grader and it gives you an option to input your changed blind-review answer as well.