True. Although I think it’s less likely that newer strings will break in a gig. I sold that Thumb bass years ago and I can’t remember the last time a string broke in a live situation since then. I’ve had a couple go as they were initially strung onto basses but they were clearly duff strings.
As for taking a spare bass I really only ever have a spare when I touring and rarely does it get used. Always have spare strings (new and old!) and plenty of batteries though. Especially for my Yamaha SLB300 which goes through AA’s like they’re going out of fashion!