As you mentioned, it is surprising how often you can get multiple flat tires on while riding, particularly on longer sprints. The tip about bringing a patch kit in your bike repair kit can be incredibly helpful if you’ve already had one flat tire. I agree that all you listed seems like an awful lot to carry, but it’s always better to be safe than sorry, isn’t it?
Be organized. “I like having everything be really small and super organized. I put all of my tools in CamelBak’s Tool Roll. It’s got little compartments, and I can separate tire changing stuff in one place, stuff like extra pedal cleats or an extra derailleur hanger in another, and it all rolls up into this tidy pouch. If I do have a repair, I can pull that one thing out and lay it out on the ground and it’s easy to work.”
Modern bottom brackets use a sealed bearing type construction that keeps water and debris locked out, so they seldom go wrong. Maintenance is impossible so they need replacing when they do wear out. Older style cup bottom brackets need to be re-greased every now and again, and occasionally will need to have their bearings replaced. There are a lot more teeth on the chainring cogs than those on the rear cassette, so need changing less regularly. Cranks usually a solid one piece construction so there is not much to go wrong.