The important thing is that the A -- wherever it is on your guitar, banjo, or Swiss bells -- is tuned to 440 cycles per second. As long as you know where it is on your instrument, you're okay (where you are may befuddle others trying to play with you, but that's for them to figure out). I have been to a few songfests where someone refused to retune, insisting on keeping their instrument tuned somewhere in the cracks. One guy simply had a tin ear, didn't want to retune, and didn't think it necessary. And another guy was a militant non-conformist, and tuning to some arbitrary standard such as a tuning fork was against his principles (this was in the Sixties). Needless to say, neither of these folks played well with others -- in any sense you mean.

If you never play with other people, then it doesn't really matter.

I do think, however, that keeping your first string fifth fret tuned to a 440-A (assuming you're not using a special tuning) produces the optimum tone quality on a well-made guitar, and is easier on the guitar. One of my guitars is a lightly constructed Flamenco that has appreciated in value frighteningly over the last few decades, so I'm pretty careful with it.

Don Firth