Don, that's exactly what I was trying to explain.

Yes, we have strategies for dealing with it, so it's not a problem - but it does have to be understood and dealt with, and life would be easier for both players and audiences if this simple matter of metallurgy was better appreciated all round.

I often see guitarists changing tunings between nearly every number, getting the guitar perfectly in tune, starting the song, then wondering why it sounds so bad a minute later.

Some people don't mind being slightly out of tune, but if you play like I do, almost classical style at times and well up the neck, with lots of of duplicated notes made on different strings, tuning is critical, and the temper of the instrument will make all the difference between a piece sounding wonderful and sounding just rubbish.

I try to detune right at the end of a song, then play another instrument while it relaxes, or do longish into, so when I pick it up again it's stable, and ready to go - or if I can't do that, I deliberately start the song with some strings either slightly sharp or flat so they'll come into tune during the piece - which will usually be much longer than the time the guitar takes to settle.