I'm "old school" and ride sew-ups, so patching a flat on the road isn't a practical option for me. I carry a spare sew-up under my saddle and a Silca Impero frame-fit pump. If I get a slow leak, I can air it up multiple times if necessary in order to limp home (can't do that with a CO2 cartridge). If I have a blow-out I can switch to the spare. If I have two blow-outs (which never has happened in over 20 years of cycling) then I'm on my cell phone . . .