Actually, I think SpaceX as a satellite launch company is living this advice as well as one could. You need at least one engine and one launch vehicle, so they

Actually, I think SpaceX as a satellite launch company is living this advice as well as one could. You need at least one engine and one launch vehicle, so they built Merlin and Falcon. The rest of their LV development has been steady iterative improvements to those platforms. This strategy enabled them to achieve reusable boosters, because building sophisticated autonomous flight controls on top of a known, proven, reliable LV is much easier than doing it on top of a newly minted one. SpaceX as a Mars colonization venture on the other hand...