I've never seen people pushed like that to make the curve line up, that I can recall. There's a belief that if you have a large enough sample, that the distribution will have a certain shape (that is, it's unlikely that if you have 500 people in a calibration that there won't be a few underperformers). I've never seen that used to change a score, either in an retrospective or anticipatory fashion, but only to assess whether the process is being internally honest, and only at scales that are large enough that the concern isn't particularly affected by sampling error. (That is, if past experience is that a certain outlying part of the curve has roughly 2% of employees in it, I've never seen anyone object because that bucket is empty with a N of 150 or less.)