Couldn't agree more - the problem-fixing approach is fantastic for focus and motivation. My new startup follows this pattern, we're pre-commercial and the funders have got us to do market research in tandem with prototype development. I was a bit wary at first, wanting to jump into the problem fixing part with the engineer, but the more research I undertake, the more I realise that other people have also had the same problem, and tried to fix it; at least by knowing about these attempts we can save ourselves a lot of dead-ends in the problem fixing process.