When I was in grade school, I took notes for my classes using Tengwar (elvish) runes as a way to alleviate boredom and force myself to pay attention (just taking the table in Appendix E from Lord of the Rings and transliterating English letters into them). I could do this at a speed sufficient to keep up with a teacher talking, so pretty fast. I cannot read any of these notes today, much less write them.

If you don't use this stuff for a few decades, you do forget, even when it's just an alphabet.