That statement is True.
Challenging goals is created in order to ensure our personal/organizational development/Growth.
By setting a more difficult that we had achieved before, we will keep putting ourself in a situation where we have to improve into a better version of ourself.
The five groups of people that were part of the factory employees were owners, managers, children's, artisans and immigrants. These are the five basic employees that were found in factories. In some cases there can be other kind of employees for specialized jobs in certain factories, but they were not common to all factories.