Often times, when we are extremely focussed on a particular topic, our thinking gets pointed and we tend to miss out on a lot of things. A review draws our attention to these things we missed to notice. Involving others who know you well in reviewing your application can also bring to light different perspectives about the experiences you have had. You may never have thought about your own experiences in the angles that they perceived it, which is exactly why widening your understanding based on feedback is important.