I think the problem is that there isn't a higher level summary that can tell you when a piece of a project will deliver. The detail of that delay matters. To g

I think the problem is that there isn't a higher level summary that can tell you when a piece of a project will deliver. The detail of that delay matters. To give an example: I can't say it takes 1 year to build a widget so this widget will be built in a year. It matters that Max is working on a piece of code but will be out in May and his work won't be sufficiently documented so Shannon won't be able to make enough progress on this particular bug pushing out the project two weeks. The particulars of a particular project matter all the way down.