I took 3 spare tubes and a puncture kit yesterday. If I had remembered, I would have taken a spare tyre too. I always carry an SRAM powerlink in case my chain breaks. (I don't think that I have ever broken a chain on a road bike, but I have fixed several for other people who have. I think I broke a chain on a MTB ride once.)
I used to take so many things with me it got silly , in the end i knew going out they bike was well maintained so why carry all these things , now its levers , tube , co2 , and bank card , these four items will get you home from anywhere.
Not where we were supposed to ride today, where I rode yesterday instead!
My bike started making unpleasant noises when I was a long way from potential help and that got me a bit worried. (I haven't found out what the cause was yet but I think it is either the bottom bracket wearing out, or the chain needing lube.)
I only saw one call box out there, and my phone lost signal for 6 hours of the 11 that I was out! It would have been a very long trek to get to somewhere to summon help.