Total Bed Bathing

Last Monday we had learned how to do total bed bath to a patient. Our prefessor shows us how to do it first then she gave us 30 mins for us to review it then we need to do it as what she did (return demo). Every student spend 20- 30 mins before we finish it. I got 99% in my grade and this grade is for our prelim exam. I ask my self, why is can't get perfect 100% in my fundamentals of nursing?