Once I realised I rarely read my notes, I now put them in a single note and prepend it when I add something new. It’s weird but I think the value I get from notes is in the writing of them, it’s a way of thinking rather than for recall.
Agreed, I always add to the top of my note files. You can also use timestamps so you know when something was created. Nowadays I use this just like a notebook, adding new pages to the top. You can use it to write not only simple notes, but anything you want, like for example the 1st draft of a book or report you're creating. Even some coding can be done this way.
It really is in the writing and not the referencing 95% of the time. That's why I tend to hand-write my notes. If it 's something I think I should have for reference, I'll transcribe, bookmark a reference, or something.