The way I read that is that only 10% of the work is writing out the actual implementation that you're sticking with. How you get there isn't as important. Ie so

The way I read that is that only 10% of the work is writing out the actual implementation that you're sticking with. How you get there isn't as important. Ie someone might want to take notes on paper and draw graphs while others might want to type things out. That's all still planning.