I think that 7 and 8 are actually saying the same thing. #7 is saying that structuring your data correctly is optimization, and #8 is directly telling you to structure your data well.

The best programmer in #8 already did #7. So he never had to write a lot of code to handle poorly structured data. That's why he says, "What's the difference?"

Oh, now I get it. When reading #7 I got the impression that you were dismissing the so called micro-optimization - something along the lines of "ship early, fix things later. Don't get stuck over-engineering and delaying writing code".