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With most strings I wouldn't be too worried about this but TI flats is an exception. I've had several sets go bad when loosening the tension completely. The windings didn't visibly unravel but I think they must have shifted because at least one of the strings developed weird overtones afterwards. I could also hear some strange metallic "pings" when bringing them back up to pitch. Not the kind of pings you would expect from the strings sticking in the nut. More like the pings you sometimes hear from a hot car engine cooling down. Maybe "ticking" is a better description. For what it's worth I've also experienced this with GHS Balanced Nickels (also round core) but only on ONE occasion so I guess that may just have been a faulty string.
I've always suspected that the extreme flexibility of TI flats won't retain the 90 degrees bend that round core strings need to keep the windings firmly in place but I really have no idea. All I know is that I will NEVER loosen TI flats unless it's absolutely necessary.
And just to be clear: This has not happened EVERY time I loosened TI flats but it has happened often enough that I won't risk it again unless I really have to.
I've always suspected that the extreme flexibility of TI flats won't retain the 90 degrees bend that round core strings need to keep the windings firmly in place but I really have no idea. All I know is that I will NEVER loosen TI flats unless it's absolutely necessary.
And just to be clear: This has not happened EVERY time I loosened TI flats but it has happened often enough that I won't risk it again unless I really have to.