Personally, I've been using one form or another of journals and notebooks for over three decades. I did go through the "plain text is king" .txt phase, but, while search is useful, I always revert to a handwritten notebook.
I find that I have a sort of visual memory of the location of a note or scribble, and can sort of easily find my way back to it "in the lower-right side of the page near the end of the notebook".
Another meta-metric that's interesting to access and is lost when typing is the changing quality of my handwriting, and how it exhibits the underlying mental state.
The notebooks/journals started from standard local composition books (B5) to narrower 14x21-ish cheap hardcovers. There's also dates (manual), titles or topic tags (manual), page numbers (manual), cross-references with arrows (which do stand out amongst the handwriting, e.g. -> p. 20, or -> C/20 to xref back to notebook C when you're on notebook E), indexes (also manual), earmarked pages, and a physical bookmark string. I've also reverted back to pencil, which I find more "quiet" a medium - I've been using Faber Castell's sleek TK4600 since elementary school, and it was quite interesting to return to it a couple of decades later.
Plain text is still king nowadays, but it's also diagrammatic, and hyperlinked, the only difference being it is manual, and seems to assist immensely with the memory and personal internal coherence. I can write down a note to myself, working something out, and then return to it a couple of months later, cross-reference it and expand it, gradually reaching new understanding.
No need for slip card boxes when you have a running log of your thoughts and works that can be referenced and cross-referenced, nor is there a need to limit the length of your text because of the medium - write a bullet list if you want, checkbox it, or a 200-word vignette, or just let loose over a few pages, it's all good: a plastic medium for a plastic mind.
In all, for me journaling/notebooking is highly recommended. And for the younger folk who are keyboard-first, perhaps the deliberate slowness and scratchiness of this quaint medium will reveal a meditative quality.