I agree the blade does not stretch. I do a lot of fretwork and sometines it appears that the bllade stretches, but if you set your tension and release it
and it sems like it stretches if you if you see some stretching tak it out and dheck the leght. it wiill be the same I tried it and checked the lght. with a set of electronic calipers and there was no differench. the blade doesn't stretch at times i believe the blade slips a little. I use Olson blade so I can't speak obout other blades depends on the material the blade is made of.
IKE