This is a post by Dave Martin on PTC site.
His tips for creating more reusable designs included following design intent, minimizing external references, and complementing parametric modeling with direct modeling. Now he’s adding two more to the list for those who want to get even more out of design reuse.]
Use Native Surfacing Tools
Imported data is more difficult to reuse, because it cannot be changed as easily or quickly as native geometry. When designing your model’s overall shape, CAD packages can offer three paradigms for surface creation: