I think you're reacting to the word "productivity" because it has negative connotations to some readers.
To others, "productivity" has neutral to positive connotations.
I think we all universally desire "less effort for more output" across work and leisure activities. We just don't like to label it "productivity". (I made previous comment.[0])
E.g. if a gardener wants to plant a row of flowers for pleasure, she might put all 10 flower pots into a wagon and then drag the wagon to the final location. This is more productive than hand carrying only 1 flower pot at a time and walking back & forth 10 times. People inherently like to be "productive" even for play and leisure!
>Why should we force ourselves to organize our days to improve our coding time ? We should organize our life to improve our reading, playing, resting time.
I think you're being uncharitable in interpreting the blog essay. The scope of his tips is about being productive while in the office. (Ctrl+F search article for "office".) Therefore, finding bugs faster between 9-to-5 isn't going to detract from "playing" time on the weekend. In fact, it may even let the programmer leave earlier on Friday.