There's much confusion between "permanent" notes and "literature" notes in the zettelkasten world. In fact, permanent notes are not specially appointed by any means; a more productive way to think about it is to think of "permanent" as signifying "permanently useful," regardless of the originality of its content.
Notes are not carved in stone. They change, evolve, mutate, flex, adapt, shrink, and grow. As Schmidt points out, Luhmann did not wait to "develop the idea to maximum sophistication" before adding it to his zettelkasten. The usefulness of an idea, after all, may only become apparent much later when it is related to an idea that hasn't arrived yet.
@Will. “All Notes Are Malleable: Strive for Permanently Useful Notes, Not Permanently Unchanging Notes.” Zettelkasten Method (blog). Accessed October 21, 2020. https://www.zettelkasten.de/posts/literature-notes-vs-permanent-notes/.
Schmidt, Johannes F. K. “Niklas Luhmann’s Card Index: The Fabrication of Serendipity.” Sociologica 12, no. 1 (2018): 53—60.