Parts sometimes have inefficiencies caused by adding and deleting features, or features added to correct an earlier error while searching for the correct final form. At some point, these inefficiencies should be removed and the part recreated from scratch. It is usually difficult to make the decision to rebuild a part from scratch when you are under a tight deadline, but you need to weigh the cost in both time and money of remodeling the part against potential for problems that may be caused by the model. It certainly takes a ﬁnite amount of time to remodel the part, but usually not as long as you think because you know exactly what the final model will look like. With an inefficient model, a simple change could cause the model to fail to rebuild. While a single inefficient part in a large assembly may not have a huge effect on rebuild time, rebuild times will be affected by many parts that are inefficient. The other consideration is whether this is a single, one-time-use part, or it will be used in this and future designs. You may consider not recreating a one-time-use part, but reusable parts should be created efficiently.