I think every reader has his method, that that suits him better.
To illustrate the point, this video from about the 13'
the teacher/commentator says that she´s used to read the books and sell them in top form, not even an annotation, an explanatory note, nothing. https://www.youtube.com/watch?v=B5YxjzahLrg
She´s very disciplined, I just can´t help it. Sometimes I see a word that has a new meaning, not easily seen in dictionaries, or at least not in most of them, then I may highlight it and/or make explanatory notes with the meaning. It´s me, though, I don´t recommend people do what I do, but what I say, ha ha
I saw that chunk on the magazine The Economist
: "That is partly because growth is flagging..." Well, to me "flagging'' had a unusual meaning there, that of "becoming weaker" so, I hightlighted that part. It´s me, I just can´t help it.
When I see some sentence that is interesting and begins to appear in more than one place/novel etc (that is, it´s commonly found, it´s part of the day-to-day) I may or may not highlight, it´s a sort of flagging (in another sense here) to look it up in a dictionary or make a search.
There are words that I can understand out of context, I look it up in a dictionary but I don´t highlight it, unless it is ''interesting". This way, I don´t need to stop the "flow" of the reading.
Other habit of mine is, if a word/sentence caught my eye, but I can explain it in English I go ahead, look it up into a dictionary but I go ahead. Turn the leaf without giving much thought, unless it appears again and again, giving that
"de javu" feeling. So, I think "this guy really likes this expression", maybe it´s in vogue these days, it´s worth it to stop and study it more, see it in other contexts (not to use it in a wrong way etc).
Well, this is my passsing commentary on that one, not a comprehensive one, just to let you know my reading ways.
It works for me, but then, when it comes to the "notes" part, I must admit that I have some second-hand books/novels, so when I write on them there´s no need to cry!