The Luhmann method uses a unique alphanumeric sequence to facilitate note identification, organization, folgezettels, and sorting, without requiring explicit categorization, which can be limiting. In the original method, this ID code is considered permanent, since it's used throughout the (analog) system of cards to reference.
I prefer a more hybrid system, which largely dispenses with the card ID in favor of an internally updated unique note title (which Obsidian handles natively, if its own renaming tool is used). However, in cases of large numbers of notes which need to be tightly associated, such as a specific project, I'll use a prefix- and alphanumeric (e.g., prj-0a) to force those items into a sorting pattern which keeps them associated in the file browser.
I also sometimes use folders for this; it's one of those evolving things.