[Stephen]

I took all of my strings off innumerable times before I knew you weren't supposed to, because it makes cleaning and polishing easier. Nothing untoward ever happened, and I suspect it won't unless you leave the strings off and put the guitar outside on the verandah. On the other hand, a guitar that is already having a neck problem might just get tipped over the edge if all the tension comes off suddenly, so I'm a little more careful these days.

If I'm doing a gig (only about once or twice a year) I like to put new strings on a few days before (no later than a few hours before a performance). Very new strings are way too bright for me, virtually unplayable.

If I'm not doing a gig I can usually get two or three months out of a set of steel strings and a year out of a set of nylons.