Often we hear people wanting estimates to be within 10% even if the dev team has not been hired yet and you have no idea about their productivity. This results in techniques such as fat and burn (add fat burn if you are under) being applied.
To truly get a 10% estimate on a piece of software work what needs to be in place? It does not need to be the entire project at 10% but how much pre-work is required to get there so at least the build can be within 10%.
The idea is that if some one is asking for a 10% threshold on estimates of a development cycle we can talk about related overheads and risks.