It will depend on the industry. Competition drives new processes, techniques and technology that improve efficiency. Also, the larger the market, and market share of a company, the greater the economies of scale. Also, the certainty of a particular station being able to process parts at a precise speed will depend on factors such as its complexity and the nature of the parts or materials used to make it, changing perhaps from one hour to the next, or one day to the next, for example, between 80% and theoretically at least, 100%.
For example, a lot of laboratory glassware is surprisingly still largely hand-made. Tools and techniques have improved, and no doubt will continue doing so. But automation always becoming cheaper. But the bespoke nature means it is unlikely to ever warrant factory lines.
But on the other side of the scale, although I don't have figures, common hardware such as nuts and bolts are produced on such large scales, and the materials so consistent, and the process so completely automated, that the utilisation of posts is with little doubt above 90%. But this is then open to debate exactly what the definition here of efficiency is. For example, if it is the capacity of an average person with a given skill set, or a given machine at full speed, the economy of a machine at a certain speed: full speed may incur higher energy consumption per part, dramatically increase wear on its parts, or reduce quality of parts produced.
But how far do companies go? It's down to their bottom line; whatever makes more money.