Actually we discussed this many times years ago. Quite a few of us had the impression that there was sort of a paycheck system where payments were just too consistent and had “pay em just what keeps em on board” charecteristics.
All of this was speculation mind you, but there was annecdotal data to support this idea. Unfortunately there was no proof and no one stepped forward with anything more then hunches. The conversation stopped at that and this is the first time I have seen it discussed again.