I’ve needed to replace a rear hanger twice this year. First time one got bent it was not catastrophic. It happened climbing out of Lllanidloes on the Bryan Chapman Memorial in May. I managed without the bottom gear till I got home and could replace it. Second time was in Holland in August. I allowed my second oldest son to have a ride on my bike. He was over enthusiastic and came off. Bent the hanger right out of shape. Gear change was totalled. Did not have a spare with me. Cut my intended mileage down for that week away.
Worth carrying a spare. They’re not expensive. They are small and weigh very little. A quick and easy fix to what could be a ride stopping prang.