There are some common mistakes that are often made in connection with the Pareto principle. For example, it is often misinterpreted that with 20 percent of the invested time or effort, you can also achieve the 80 percent return that you would achieve with your usual effort. This makes no sense, however, as then 100 percent would be achieved with 20 percent effort. This is a misinterpretation in which the individual percentages are simply added up to 100 percent, although they stand for different aspects. However, expense and income are not the same, and cannot simply be added together. In order to generate the full 100 percent return, the expenditure must also be 100 percent. The misinterpretation described above quickly leads to over-optimistic assumptions as to which goals can be achieved with how much effort.
But even if the basic principle itself has been understood, the conclusion that 80 percent of the possible performance is due to 20 percent of the effort can lead to a reduction in all tasks to only 20 percent. After all, there are a number of tasks that do not contribute directly to the actual goal, but must nevertheless be completed. This includes, for example, writing and replying to e-mails. E-mail correspondence usually contributes little to a company's success, but not responding to business e-mails at all would have serious negative consequences for the company (as would neglecting the accounting – even if the accounting department itself does not generate any profits). These absolutely necessary, but seemingly unproductive tasks can be optimized by keeping the expenditure for them as low as possible.
In addition, the Pareto principle can lead to certain negligence, as the majority of tasks are considered to be of little importance. Only those who dedicate themselves to their tasks in a conscientious, concentrated, and structured manner can also achieve 80 percent of the results with 20 percent of the work – it is quite unusual to pull this off.