I stopped carrying spare spokes when I stopped carrying cassette removers, chain whips and large adjustable spanners, because the spoke breakages I’d had were all on the drive side rear. I do carry a proper spoke key though in case I need to true the wheel with the remaining spokes following a breakage. I’ve only had maybe 4 spokes break in over 140,000km of Audax rides and all but 1 were on cheap, dodgy 27” wheels in the Dark Ages. These days I typically use Mavic Open Pro rims on Shimano 105 hubs with stainless spokes and use rim brakes and non-tubeless tyres so pretty standard and strong wheels. I have a 32 spoke rear wheel in at the moment and consider that fine as I’ve carried ridiculous amounts of camping gear to the PBP on similar wheels and got away with it. After reading some of the posts above I am slightly worried about my current front wheel as it’s an entry level £50 Shimano road wheel with just 20 radial spokes so I’m no longer sure I dare use that one for the PBP! That said, it’s been great so far getting me round LEL, TINAT 600, Mille Pennines, Mersey 24, Dolomites SR and plenty of shorter rides too. It’s still perfectly true despite hitting some pretty nasty potholes and running 23mm tyres at 100psi.
I might possibly buy myself a fibrax spoke or two, but they seem bit pricey for what they are. Potentially ride ending things I do always guard against are major blowout, snapped derailleur hanger, snapped chain and freehub failure. I carry a spare tyre, 4 tubes, spare hanger, quick links, mulitool with good chain tool, and about 20 cable ties plus a few other bits and bobs.