Answer: True.
Step-by-step explanation:
People sometimes have a tendency of doing only what they are told to do or only what they are paid for. This is why most people who progress in a company do so on the basis of having done work that was not in their description, but would have helped the company progress.
It would appear that Marsha's 6 employees are all of the caliber of employees who just do what they are told and nothing more.
For this reason therefore, she would include a stipulation changing the scheme to include careful performance of the other duties before any sales commission can be earned. This way they'll start to do those other things since they are now paid to do so.