I've been doing this more and more over the past year, but I just write on plain white paper and throw it away after the stack on my desk gets too big.

Like the author, I don't seem to ever need to read my old notes. Instead, it works wonders as a mental bucket of sorts and I've found paper to be extremely powerful for this. I tried doing this on a Surface Pro, for example, but it was significantly less enjoyable or effective.

Now with LLMs helping me write code, planning ahead on paper is even more useful.