The thing about the practice, though, is that you won't find it written down anywhere.
"I don't think the word even appears," said Senate Historian Donald Ritchie. "It's obviously a very powerful instrument used by every senator. It gives them a lot of influence over the administration and gives them individual clout."
Since I'm no Parliamentarian I can't make too much of this but that it is abused in secret isn't a real secret. I suppose one question for Senators is whether the body is of any real use to American politics or simply an impediment?