Why so many photos?
 At a basic level, I would say that we needed to become acquainted with our cameras. Since digital cameras have made it so easy to photograph mindlessly, it was important for a lot of us to understand how to function our cameras. But I would say that it was also important for us to see the themes in our composition and content. Possibly, we could make note of a prominent subject of ours and perhaps why it fascinates us. While I learned to quickly adjust my shutter speed and aperture settings as well as choose different ISOs, I also made note of a common theme as far as composition and content: a majority of my photos seemed to be of things that were forgotten or left behind, and a lot incorporated narrowing the frame to exaggerate how far forward the subject was.

Why do I need to look through and rate them?
I need to rate them because it is important to recognise my strengths and weaknesses. Also, I will be able to more easily notice any compositional tactics which I may have found interesting at the time but perhaps realise are overdone in my body of work. In addition to being able to view my photos as a massive collection, I can see what works or doesn't work in different settings. This way, I can remember how to treat lighting and exposure in different situations and adjust accordingly as well as have a quick point of reference by sorting through all of my pictures by rating.