So long as the software will only be shipped after all three stages, it's a useful metric to go by, I guess. It prevents you getting overwhelmed by the myriad a

So long as the software will only be shipped after all three stages, it's a useful metric to go by, I guess. It prevents you getting overwhelmed by the myriad amount of decision-making that writing software is. And also, so long as you accept the fact that you will need minor or major redesigns by the time you get to the "fast" version that is production ready.