In following along with the theme of a systematic approach to climbing, here is the catalyst that moved my thinking along these lines.
The following podcast was constructed of a video clips from a work shop I attended taught by Bruce Smith, co-author of the book On Rope. In it he describes his five requirements of a Single Line Ascent System.
This is not to say these are the end all and be all of single line systems. It is just a starting point and a outside the tree world perspective