Going too deep on any estimate is actually a bit of a pitfall. We see this in my world (large scale project management) where some folks want to plan activities

Going too deep on any estimate is actually a bit of a pitfall. We see this in my world (large scale project management) where some folks want to plan activities down to the tiniest tiniest level, and it just doesn't pay off. In software, it's hard to do estimates at all if you're a blue-sky environment. Once you have a codebase you're working on, it can be possible to give a better estimate of what it will take to implement a new feature, but the more elaborate the feature, the softer the estimate. We have just shipped a very big change to our product, and we thought it would be a 3-6 month effort to do so. It took 3 years, because it was VERY invasive and VERY complex, and we just didn't understand the underlying challenges enough when we set out to do it.