Real manufacturing processes are not usually normally distributed because the manufacturer tries to create a product within specific measurement goals and can control the shape and size of their product to a great degree
This film at the link explains a lot about the problems with the people behind corporate measurement targets
https://metanoia-films.org/human-resources/
Picture of film title from the link above
Human Resources: Social Engineering in the 20th Century explores the rise of mechanistic philosophy and the exploitation of human beings under modern hierarchical systems. Topics covered include behaviorism, scientific management, work-place democracy, schooling, frustration-aggression hypothesis and human experimentation.
https://archive.org/details/HUMANRESOURCESSocialEngineeringInThe20thCentury
@Stahesh
"Six Sigma strategies seek to improve manufacturing quality by identifying and removing the causes of defects and minimizing variability in manufacturing and business processes. This is done by using empirical and statistical quality management methods and by hiring people who serve as Six Sigma experts"
"Six Sigma originates from statistical quality control, a reference to the fraction of a normal curve that lies within six standard deviations of the mean"
https://en.wikipedia.org/wiki/Six_Sigma