Many defects are not written up. I worked as a Lame for such a company, we were always on time, but the aircraft was f****d! That is why I don't understand the whole punctuality discussion, I rather fly with an aircraft 3 hours late but serviceable than with a covered up ****box that goes out on time. But most people seem to think otherwise. How can you get annoyed if the aircraft is delayed because of a technical defect? It is getting fixed, isn't it? That delay might have saved your life!