An ST rear would need 2 canisters from flat to get you to around 20 psi......enough to limp to a tyre repairer
But here's the catch....most ppl will only carry 2-3 canisters in their tyre repair kit, and you don't know if your roadside puncture repair is a success until you add your second canister. So if your choice of plug didn't take and you need to re-plug your out of gas
So what many do is......carry both, a small compressor as the primary method and a couple of canisters as back up.