Interesting, nothing from the OP; the question was pretty vague but the thread is becoming interesting.
Carrying spares & tools is just offsetting risk, I guess, if you accept the risk you take nothing, if you want fully comprehensive all-risks covered then you take a full set of tools & spares and have a miserable time hauling that load. As
@makingtrax states there are plenty of bike shops in Spain so you're never more that a bus / train / taxi ride from help. Even then many problems evolve, rarely is there a catastrophic event so there is time to sort the problem - starting with a full serviced bike is always good insurance. For me it will always be some basic tools, ability to fix punctures (both bikes are now tubeless) and a well stocked credit card.
Riding five Caminos back to back is pretty impressive, do you have a journal of this ride?