When we learn and remember information we build new neuropathways in our brains. These pathways are strengthened when we chunk and clump information. In other words when we can see how the parts are interconnected and how they are different.
Honing notes is a great way for our brains to process the information we are given in a new way. When we take notes in class or read a textbook the information is presented in a particular order. This is often how someone else understands and organizes the information.
When we hone our notes we are able to take the information and make it our own. Moving the information around on our own helps our brains visualize it differently and strengthens the neural pathways. The stronger the neural pathways the better we are able to retrieve it on tests or in class discussions.