"I've never seen anyone able to design something away from keyboard that doesn't change significantly once it's written"
It does change once it's written.
The idea is to get a clear work plan on a "close enough" design. I estimate that my first cut of anything is maybe 50% or so.
The idea is also to avoid sitting at the computer all day and then being disappointed with how little I accomplished. Activity != Accomplishment.
A little more background:
First term freshman year, 90% of science students took Chemistry I. On Mondays and Wednesdays, only 50% of the seats in the dining room were taken for dinner. Chem Lab started at 1:00 p.m. and dinner was at 6:00 p.m. So, most freshman chemistry students took more than 5 hours to complete their lab work.
This never made sense to me. I took Chemistry I second term freshman year. My lab partner and I made a pact to never miss dinner. We did everything we possibility could to expedite lab time. We did all the reading, planning, and reviewing other people's results before we entered the lab. We even wrote our reports in advance, filling in the results as we went. Our longest lab took 2 1/2 hours. Our shortest took 1 1/4 hour. (We also both got A+.)
I still practice that methodology today. My computer is my lab and my bed or sofa is my lab prep. Preparation takes as long as it needs. Labs go fast. If they don't it's because I wasn't prepared enough when I started.