Don't most of us do the very same thing ? I always have track plans in my head. Not much room up there for anything else.....LOL I still have pencil and paper sketches from the '70s in a folder. All are tubular track for layouts that intend to use operating accessories. Some are quite good, if I say so myself.
I used to sit in school and sketch layouts. Probably why I just skimmed by in the end..... When I was a kid, my buddy and I would dream of the large attic we would never have and the immense track plans we could have running the myriad of trains we would probably never get.