I had this experience recently. We don't use a lot of detailed estimates in my team, because the work needs to be done regardless, and the estimates are then la

I had this experience recently. We don't use a lot of detailed estimates in my team, because the work needs to be done regardless, and the estimates are then largely a waste of time. But there was one occasion, where a product launch had been announced by a C*O before the product was finished, and the engineers were very clear that this launch date was impossible. So there was a lot of drama and bad feelings, and the engineering team eventually said, "okay, let's make a detailed estimate so we can be certain". The estimate came in at three weeks development time, one week after the announced launch date. One week of the estimate was meant for testing and fixing problems that are found in testing. The business experts immediately jumped on this: "Testing and fixing unplanned errors won't be a big deal and certainly not a whole week. We'll skip that so we can get it done in two weeks". Thankfully, this is retail banking, so releasing an obviously broken product flies even less than missing the deadline. The product was eventually launched uneventfully, one week after the detailed estimate and two weeks after the announced launch date. All in all a success.