Even if you change strings before each performance that is no guarantee that one won't break.

Has anybody ever heard Beppe Gambetta tell the story of when he was performing with another guitarist-can't remember for sure who, might have been Dan Crary--& a string broke on Beppe's guitar midtune. He ran to his case backstage, no strings there, so he ran outside the theatre (guitar still strapped on), got into the car, into the box of extra strings, ran back inside pulling the correct string out of the package & tossing the others as he ran, jumped up onto the stage while attempting to begin putting it on his guitar which was still strapped on, got the thing wound, & joined his partner in the tune. They screamed & applauded for Beppe. His partner joked that HE was the one who had carry the tune while Beppe was running around.

Beppe keeps extra strings in his shirt pocket now, which he sometimes has to use during performances. Not a bad idea.