There are many ways to gain understanding of how to design for startups and if anything. By working on so many startups, some briefly, some all the way to series C funding, some to exit, I have learned that there are no one way that is the right way.
Also mind you I still have had to build my own company (from 2 people to 60 people back to 30 people and from 2 partners up to 8 partners and back to 4 partners) so you can say that I have stayed focused on that.