I feel dumb(er) when typing, and smart(er) when writing

I have noticed many times, writing down a problem and work on it on a paper is much more productive than staring at my screen and/or jumping right to code.

Last time it happened, I spent a day on a Coq exercise, when I finally I decided to grab a paper and pen, and solved it in 5 minutes.

Is this something that anyone else is experiencing? Is it something that has been (dis)-proved?