My normal approach to exams is to go through once quickly and answer the things I know or that look easy, and then to go through again for the harder questions or the ones I'm less confident about it. Unfortunately, when I took the CCNA exams, they're structured for a one-pass approach - it made time management a lot harder, because I couldn't budget for per-question time until I was about halfway through and had some guess about what fraction of questions were easy/hard/fast/slow. Very frustrating, and that's of course not how the real world works.