This is going to sound a little nuts to anyone who isn't old: I've never brought two guitars to a gig in my life, and I started gigging in 1966.
When I started, no one I knew even owned more than one guitar and one amp. You played what you had, and that was it. But the stuff didn't break on the way to the gig, because cases were actually protective. I saw Cream. Clapton only played one guitar at the gig. I saw lots of famous classic rock acts. Ver few guitar changes were to be seen.
I should also mention that I also played keys, and never brought more than one organ to a gig. Thank goodness, considering what they weighed.
If your amp went, you replaced the fuse, put in a new tube, and carried on. Though I never had an amp blow at a gig (OK, they all blew because I was playing through them, but I meant 'blow up'), a bandmate did. And even that was only once!
One time when I was in college, my combo organ started sounding funny at a gig. I was supposed to drive to my girlfriend's dorm or sorority house and pick her up. But I had another gig the next night, so I called and said "My organ isn't working, so I have to have it fixed."
My girlfriend knew what I meant, and when her friends asked if I stood her up, she said, "Les' organ isn't working, so he drove to Detroit to have it fixed."
But her friends jumped to a...well...different conclusion. They told her they hoped I would be all right after the surgery.
True story! You can't make this stuff up.