(also if you want a longer overview a bunch of related concepts are talked about in Dominica DeGrandis’s book Making Work Visible, and the advice on managing by the critical path method comes from a makes-my-eyes-roll-a-little-but-still-pretty-solid business novel by Eli Goldratt called Critical Chain, which applies the reasoning from another less-eye-rolls business novel by the same author to the “project context” that we find ourselves in when writing software.)