This weekend, we had our final rehearsal before our 1st gig in a couple of years. We ran thru the set and were working thru it again and just killing it. All of a sudden, bwam, broke a string on my number 1. My number 2 was in a case at my house and no 2nd set of strings. Practice over.
You couldn't struggle though the rehearsal with a string missing? ... for the sake of your band mates if nothing else.
More important than bringing multiple guitars to rehearsal... a bag with a set of strings and a spare cable in.