Hate to end a ride..
I carry what I need and don't care where is goes. For me there's nothing worse than time waste or ending a ride because I don't have some basic tool or part. The main culpret's seem to be: Spare Derailleur Hanger, chain link, a good spare tube (got to watch that tube rash wearing a hole in the spare), low air in the first place, enough hydration, some food and spare derail hanger.
Actually worse is when you give something out that you later need on a ride. I've given lots of stuff out and am mostly lucky during the rest of the ride. I wear funny socks too!