Koos is used for those people who do a lot of activities in their everyday life. They are not for those people who just lay down on the sofa the entire day channel surfing on TV. They are clearly not focused on their lives but just waiting for someone to work in order to feed them. It is no secret they will live longer but their brains will suffer if they are unproductive every day of their lives. They must do something everyday in order to achieve their goals whatever that may be.
Koos can also be used to monitor individuals in their progress. Some can be observed to carry out their tasks faster than the others and it all depends on how well their bodies respond to the cure for their injury. Koos is used in the clinic too as they are used to tap on to the progress of patients. The doctor will know if the patient is responding well to treatment or not. If the patient is not responding well enough then the doctor will most likely change the treatment of his injury.
The doctor definitely does not want his reputation to be ruined so he will think of something in order for the injury to get healed right away. He does not want the patient to suffer for a long period of time because it is going to be painful for both of them. He definitely put his shoes in the shoes of the patient so he will know how painful it is to have an injury like that. The validity of Koos came from a lot of research involving patients and surgeons so you will know that the data gathered from there is 100% accurate. There is definitely no room for error in doing something like this because we are talking about bodies.