A Member asked whether guitar strings should be slackened after playing, as is traditionally done with violins and other classical instruments.
I'll take a guess. The reason is probably that, prior to the twentieth century, the strings of musical instruments were mostly made of catgut - literally, of animal intestines - and this is still the preference of many classical musicians. Catgut is an organic material which slowly "pulls apart" under tension. So if strings are left tuned all the time, the catgut keeps stretching until it "thins out" and snaps. They might last a few months, whereas if slackened after playing they might last a year or more.
Modern strings are made of nylon which is structurally stable under tension. After the initial stretch, they stay pretty well "as is" indefinitely. In fact, repeated slackening and retensioning is probably a bad idea: it wears the machine heads on a guitar, and the repeated loosening and tightening probably "wears out" the nylon by forcing its molecules to continually realign.
As I said, this is only my "guesstimate': you might like to ask a classical musician, or try an Internet discussion forum.