You ask some good questions and this one is tricky but I believe there is no such thing as a quantifiable, proven road map to success. It’s different for each person/startup and it changes as the market, industry, and tools evolve. You can ride a roadmap for as long as the roadmap is viable. For example, if I develop a roadmap that’s a 10 out of 10 sure thing for success (which I have no way of knowing until I start to execute), then I get, let’s say, a year of success before my roadmap devolves. If my roadmap is an 8 out of 10, I might get six months, and so on.