Probably one of the most common faults encountered during a test. There are really only five times that you will need to do an observation. These are, 1) speeding up (including pulling away), 2) before slowing down, 3) moving or turning to the left, 4) moving or turning to the right and 5) when there is the potential to slow down (such as when approaching traffic lights, or pedestrian crossings). If you forget anyone of these then you will get at least a rider fault, but changing lanes, for example, without doing an observation will often be considered a serious fault. Typically an observation (or lifesaver) will involve using both the mirror and a shoulder check (for the blind spot), however to keep updated using the mirrors on their own is adequate.