As someone who's been trying to pick up a consistent task tracking system, I have a question: Do you just always have a notepad with you? I tried something similar to this with a pocket-size notepad, but it was annoying and didn't fit very well with a pen.

So far the closest I've gotten is having a Google Doc, but it doesn't have the same flexibility that a hand-written notepad does (e.g. symbols, indexes, ease of writing/ access).

Yes, I always carry a notebook even in non work situations. It's never been an issue for me as far as transportation is concerned, I just slip it alongside my laptop or other books.

I also have a Samsung Note phone which is useful in the rare case I'm caught without a notebook or pen. I'll re-write any notes to my work notebook as needed.