[zenogais]

Another one of these?

Bad estimation techniques - eg. guesses without a basis in historical data (most developers don't collect historical data) - are usually wrong. No one would argue this point.

If you do iterative development with intelligent planning and collect some historical data to use in estimates the game changes. First, most of the examples of "unexpected complexity" you gave can now be identified early and factored into your estimates. That leaves the 1% of truly unexpected stuff that you can then deal with as it comes up and factor into your future thinking in a post-mortem. Second, since you now identify risks earlier and can factor them into estimates, most of your work becomes estimable, and with historical data your estimates will improve.

There's even multiple process products around this idea already, but they're mostly used in the "safety critical" industry, see [1] [2].

[1]: http://resources.sei.cmu.edu/library/asset-view.cfm?assetid=... [2]: http://www.sei.cmu.edu/tsp/

[jayvanguard]

The SEI work has been around a long time and it has had very limited success outside of academic or very controlled settings. It had its heyday in the late 90s but never really caught on broadly because it is impractical to collect the level of detail necessary, with consistent teams, languages, environments, and practices in a fast moving computing environment.

[empthought]

It really goes over well when you blow most of the development budget on estimating slightly more accurately.