The subject of KPIs recurs time and again. Just recently, I had given my reply in a similar post. I request you to go through the following link:
https://www.citehr.com/511936-pms-company.html
Though the heading of the above post is about an IT company, the reply is applicable to all industries. In the link above, you will find a few more links. I recommend you go through all the links patiently. This will help you in clearing any misgivings you may have on the subject of PMS.
Developing Competence in Designing KPIs
Developing competence in designing KPIs is a time-consuming process. It requires working with an expert. Otherwise, you may retain some misgivings, and it can be quite difficult to erase them after reaching a senior position.
Thanks,
Dinesh Divekar