What role did Industrial engineering plays in enhancing the production level?

As per the website for Institue of Industrial Engineers - "Industrial engineers figure out how to do things better. They engineer processes and systems that improve quality and productivity. They work to eliminate waste of time, money, materials, energy and other commodities." But to provide a more realistic and hands on answer to this question, I always refer to the book "The Goal" by Eliyahu M Goldratt which is largely a text book for industrial engineer. 

Industrial Engineer identify bottlenecks, analyse the current system and advise the management regarding exploiting the bottlenecks, they use the techniques as Six-sigma, lean management, TQM as this is what they study during academics and the end result is a slightly improved productivity of the system if not significant improvement.