A friend freaked out at me today when I loosened all my guitar strings to gain access to the fret board to clean it and apply lemon oil. Apparently he had read around the net that it was bad to take all the strings off at once as it puts stress on the neck. I'd never heard of this before and have been doing it to all my guitars. Is there any truth to this? I'd imagine that it would have to be done to a guitar at one point in it's life either for a good clean, refret/ fret job, etc.