I used to carry spare spokes on tour, but dispensed with them when I started using wheels I built myself from high-ish quality components and with spoke counts which ensured that if one did break, I could retrue and continue on without it. Hence, I have done several thousand miles on a front wheel with a missing spoke. The minimum count for touring for me is 32, preferably 36, and good quality rims laced to a decent spoke tension. And a load that is not excessive...