This is a post by Emma Rudeck on the Concurrent Engineering Site.
Does your company still use a standalone 2D CAD tool before working on the design in 3D? Even though 3D solid modeling has become the standard for complex engineering tasks, your company may still have a 2D CAD system in your tool set. It’s fairly common to use 2D for upfront conceptual engineering. The problem that this has traditionally caused is that when you finally want to transition the concept from 2D to 3D, you either need to perform a complicated import of 2D data into a 3D tool or manually recreate the design from scratch in 3D.
The other common headache when working with fundamentally different 2D and 3D tools is that any changes you make to the 2D design will not be automatically propagated to the 3D environment. You either give up on the 2D design earlier than you would otherwise want to or you have to make the change twice.