I worked for a part of the Bell System (Bellcore) during the late 80s through the late 90s. Managers seemed to hate performance review time because they had to do the "stacking." Under a new CEO while I was there, specific percentages (in a 5 category system) were instituted (or, at least, made clear to everyone, so they might have existed before). Only a small % of people could be in the top ranking as well as the next. A similar percentage HAD to be in the two lowest rankings. I happily existed in the middle, large, "Average" area (except for one year when I made it to the 2nd higher ranking). I had no aspirations for promotion or raises, so the system did not bother me personally, but I know from speaking to some managers that the meetings to decide who fit where (in each department of some 40-100 people) was unpleasant enough that some step down from management.