They allow me to see if I'm missing something (another way of looking at it they also prevent me from being totally unjust). So they are ok as an information so

They allow me to see if I'm missing something (another way of looking at it they also prevent me from being totally unjust). So they are ok as an information source, but can create nasty incentives. So you don't give them too much weight, you don't want them to influence employees too much. We used to do that and it impacted company culture negatively IMHO. Now it is under 20% of the score and so it cannot be abused, but it remains a useful tool.