At this stage of design the designer will invariably by under tremendous pressure to quickly finish the design and pass it on for production. This is so because even with the best of forecasting planning and vigorous progressing of design, the larget dates of completion generally arrive too soon. Therefore there is often tendency to dispense with detailed evaluation of design. It is argued that after all the designer with all his experience knows what he has done and anyone can see for himself that the prototype functions satisfactorily.