I was walking to the bike parking after doing some errands and I hear RRRR RRRR RRRR. A girl was riding with the rest of her family, and her fender was rubbing badly on the wheel. Fixed it. Then, the brother was carrying his bike as he had a flat, and they were looking for a bike shop (none really close to that area). I patched the tube for him, taught him how to do it, and begged him for the love of all that is holy to clean that damn bike and oil the chain. It was dry dry dry!
Then I picked up my own bike at the parking, and went on my way. A beautiful afternoon, but then on the bike lane there were people standing up, bikes on the ground, and a VERY scared girl crying her eyes out. Turns out that she crashed onto another biker who braked hard in front of her without warning. She cut her middle finger pretty badly, close to the bone, and would need stitches. So I took out my emergency kit, disinfected the wound, bandaged it, and sent her off to the hospital.
So I'm feeling better about the added weight of carrying tools and a first-aid kit all the time