[oceanician]

It's because developers are rubbish for not being pyshic ;) I'm always suprised how few estimates take account of environmental contributions!!

[ashleymoran]

Re "environmental contributions", that was part of the discussion, but thinking about it - estimating total effort and elapsed calendar time are very different!

[oceanician]

elapsed calendar time and total effort are often the same in a customer's mind. Time is actually money.

[ashleymoran]

This is why Kanban and its focus on lead time is more valuable than Scrum and its focus on velocity, IMO.