I have never built any guitars that were for other people so this has never been an issue. It doesnt seem to be an issue with electrics as much, but acoustic guitars, once strung and played, seem to change a little bit from the initial specs. The truss rods seem to need a little tightening, the action sometimes gets a little higher or lower.. I dont know if its a flaw in my builds, or if its just the nature of acoustic gutiars.. But after a little while they seem to settle in and become more quite a bit more stable. Do any of you have like a set set in time where you have the guitar strung, and play it to break it in? or do you string it up, hear a few notes, and send it on its way?