You know, there’s the time when you have to estimate a project’s needed time. It’s often very hard. Especially if a software has a 20 years of history, it can easily happen, that when you dig down to the bottom of the code and open the cupboard, some skeletons will fall out of it. And the cleaning up of the mess will require an extra month!
So when you estimate, you can say 30 mandays, 3 manmonths. But in a really _huge_ software, there can be such requirements, which would require not only a some manyears (!) but more. I realized, that some projects would claim ... a MANLIFE!
A manlife projects requires a whole life and soul of a person to be able to complete. Or half whole life of two colleagues. These are serious projects, which usually won’t start because of lack of resource, the limitations will continue to live deep in the code, more layers of sediments deposit on top of them from year-to-year, and somtimes can cause other projects to turn into manyear projects.