It feels as if the second reading of the same material without any look-ups perhaps shouldn’t be classified as ‘extensive reading’. Idk. It just seems very different than reading material the first time round with no look-ups.
My current thought is that this method of repetitions - once as intensive reading and a second one with minimal to no look-ups - is probably what would produce the highest vocabulary retention, as you are really getting in the repetitions you need to memorise the word.
I guess a similar method, if you simply can’t handle the repetition, would be to (semi-)intensively study the first book or two in a book series, then move to extensively read the later books (i.e. encounter the words for the first time with a dictionary in the first two books, then drill them into your memory with extensive reading/listening in the later books). And probably even better, as @bamboozled mentioned, would be to go for books you already know the story of (eg. previously read, read the Wikipedia plot summaries prior, or maybe watched the TV series). Or do the same with a podcast series or what have you.
I concur that it does seem to follow that you change which method you use as you get better. I, too, stopped using Sentence Mode/intensive reading a long time ago, as it just didn’t feel necessary. For Italian for me, it’s main use was getting used to basic sentence grammar and several particles. After that, for Italian anyways, it’s generally just single verbs/adjectives, which stops from understanding the sentence, which a simple dictionary definition is all you need. And then once you reach an advanced/upper advanced level, to put words in @bamboozled’s mouth, you probably don’t care so much about vocabulary acquistion, as you are enjoying the content, so extensive reading suffices.
The rush, as you mentioned, is to get to this point, where you can almost effortlessly engage with the language (at least have the necessary vocabulary to do so, in this case).
One thing I do notice from using doing extensive reading over the semi-intensive reading on LingQ is that I can simply cover a lot more quantity of material. On LingQ, as you get a list of non-so-great definitions, this usually ends up in me writing my own definitions, which takes a hell of a lot of time. With extensive reading, I don’t have to worry about all the time-waste that comes with the way LingQ manages definitions. If instead it was truly a one-click definition, that’s a different question, but the practical side of the matter, is that personally I compare extensive reading compared to (semi-)intensive reading on LingQ. But maybe that’s just a me-issue.