reply to u/judugrovee at https://www.reddit.com/r/Zettelkasten/comments/1cb1s8j/so_how_do_you_actually_transfer_a_book_with_a/
Others here have written some good advice about the note taking portions, but perhaps some of your issue is with your reading method. To reframe this, I recommend you take a look at How to Read a Book: The Classical Guide to Intelligent Reading (Touchstone, 2011) by Mortimer J. Adler and Charles Van Doren and Adler's earlier article “How to Mark a Book" (Saturday Review of Literature, July 6, 1940. https://www.unz.com/print/SaturdayRev-1940jul06-00011/)
The careful reader will notice that they recommend a lot of the same sorts of note making and annotation practices as Ahrens does (and by extension Luhmann), though their notes are being written in the margins and in the front and back pages of the book. On the reading front, you may be conflating some of the reading/understanding/learning work with the note taking and sense making portions. If instead, you do a quick inspectional read followed by a read through prior to doing a more analytical read you'll find that you have a stronger understanding of the material conceptually. Some of the material you took expansive notes on before will likely seem basic and not require the sorts of permanent notes you've been making. Your cognitive load will have been lessened and you'll instead spend more productive time making fewer, but more useful permanent notes in the end.
On the first reads through, reframe your work as coming to a general understanding of what is going on while you're creating a quick-and-dirty personal index of what is interesting in the work. On subsequent focus, you can hone in on the most important pieces of what the author is saying with respect to your own interests and work. It's here that the dovetailing of good reading method and good note making method will shine for you, and importantly help cut down on what may seem like busywork.
It's not often discussed in some of the ZK space, but reading method can be even more important than note taking method. And at the end of the day, your particular needs and regular practice (practice, and more practice) will eventually help hone your work into something more valuable to you over time. Eventually you'll more quickly rise to the level of what C. Wright Mills called "intellectual craftsmanship" (1952).