Notational writing is more than commonplace
Chapter 10 of Robert Darnton's book The Case for Books covers "The Mysteries of Reading" by studying commonplace books. These commonplace books were more than simple diaries, they were short excerpt jotted down that avid readers deemed important to themselves, much like literary snippets to live by. Thomas Jefferson is one of the most well know in Early American history to compile several short excerpts from his readings as a young man and consult them later.
William Drake was an Englishman who wrote several commonplace novels because as Darnton writes, "He favored bite-sized bits of text, which could be useful in their application to everyday life. For reading should not be aimed at erudition; it should help a man get ahead in the world, and its most helpful chunks cam in the form of proverbs, fables, and even the mottoes written into emblem books" (162). I think this quote also mirrors how people often gather information from the internet. Readers rarely want to read massive amounts of text off of a computer screen or see large blocks of text clumped together on a screen.
And how many people jot something down that they've read or seen online? I'm certainly guilty of it, although I do sometimes forget to write down where I found it, writing it on a post it and sticking it to my wall allows me to consult it in the future. So I agree with the practices of commonplace books, though I'm not ready to only read or attempt to write in that style for a length of time.
Take a look at what my peers have to say on this subject.