You'd be surprised how much creative tasks like 3D modeling and creating artwork can be broken down into tasks that are very well defined and can be estimated quite correctly.
I think it would fall down the same lines if you required a coherent world and high quality for each of the models you create.
That would mean redo models that don't fit the whole piece, endless tweak some models that are really difficult to get right, sometimes do swiping changing across all the parts because as a team you realize something is off etc.
The balance will be between delivering something within a time frame, and delivering the quality that was requested/expected.
The difference is that you break down software into smaller and smaller bits and then find a small bit that needs data from a far away small bit. I suspect this happens less with mechanical systems.
