Making a worker work Vs Profiting from him

Plants want to utilize each workers capacity to its fullest. They demand everyone work continously for as many hours as possible. However, when workers work on a non-bottleneck machine and produce more than the bottle neck, or more than the market demand, their production is out of sync with the flow of the system. They are not adding value but tying up money in inventory.
Source utilization is using a resource to move towards the goal.