Software development cannot be managed like this. This sort of task break downs come from classic management training. The problem most people are unaware of is software development is more a creative activity than anything else. Yes there are serious technical aspects to it but since the problem is virtual and not bound by any real world limitations, like how civil engineering would be, there isn't one optimal solut…
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.
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.