Here's a little fact: My lines are vastly closer to stock trim after I stretch them than before. This particularly applies to symmetry.
Safety-wise I am not aware of an increase in line breakage due to this practice. Broken Spectra lines seem uncommon even on badly worn linesets. If line breakage isn't a problem and openings, flight and landings are improved by better line trim then I would say safety is improved by using this technique. The only potential issue I see is brake lines snapping during a swoop, that would merit some study to see if there might be some vulnerability.
Value added? For 30 minutes of free labor (you can do this during a weather hold or whatever) your lines are in far better trim.
You're right about one thing, people are mostly too lazy to do this.
(edited to correct "break" to "brake" )
(This post was edited by Martini on Dec 28, 2012, 9:20 PM)
Post edited by Martini
() on Dec 28, 2012, 9:20 PM