Every company has their own way of working. Basic idea is to design various performance slabs. Quantification of performance slabs like > 85%, 75-85%, 65-75% is better than subjective rating slabs like Excellent, Very Good, Good etc. The latter has scope for manipulation than former. As far as adding extra weight to the higher slabs is concerned, I do not think it will bring any significant change.
Essence of Performance Management System (PMS) lies in giving primacy to the organisation performance, identification of costs or ratios associated with the business and assigning those to the respective HODs. HR or company's leadership may pull a rabbit out of their hat but at the same time they have to make sure that principles of PMS are not diluted in any way.
14th November 2017 From India, Bangalore