[goldcd]

I agree - although not sure it's just the summarization, more the translation between 'information schemas' exposes patterns. e.g. I might read a few pages of text and scribble out the key points onto a mind-map I go. Then looking at the shape of what's on the page, normalize it onto a ER diagram on a slide with an accompanying swim-lane diagram showing the process.

Each iteration of formatting hopefully progresses the display of the information towards its ideal. You know when it's worked (and when something isn't working out and you need to quit and try something else).

To me the benefit of writing is that it makes me deliberately make a decision as to what I transcribe and what I leave out. If I skim read I often find my mind has drifted and I need to turn back some pages. Also, writing takes effort. If you notice you keep writing the same word/phrase, you'll give it an acronym. If you find repetition of concept, maybe you'll just draw an arrow pointing back to the paragraph the concept first came up - and your longhand is starting to turn into the next iteration already.