Seth Godin talks about quieting the lizard brain within us and finishing what we started. He says thrash the ideas up front, don’t get scared about shiping the product and start thrashing the idea later in the development stage. Of course, we also have the analysis praralysis syndrome where we might spend too much time in analyzing the idea without ever starting it. You don’t finish what you don’t start, right.
Okay, so basically what everyone is saying is move your blooming part-of-your-anatomy and get on with delivering on your great idea. Sure analyze (thrash) the idea at the start but don’t get stuck there. And then once you’ve started it, don’t start thrashing (analyzing/critiquing) the product just before you have the deliver it.
When you hit the paralysis stage of the analysis of the idea, your initial vision is blurred and faith questioned. Discipline to stay the course will deliver results even if they were not what you expected. Learning or the "a-ah" moment will definitely occur. Alas, the question is it enough to keep ploughing through – I think Yes.