I've always carried tire plugs, (and since 2012 in Spearfish, gummy worms, too) and a gauge and mini-compressor. I had a flat at Perkins in Spearfish one morning. I think we ended up with 4 or 5 of the mushroom plugs inside the tire. Somebody went to K-Mart across the parking lot and bought gummy worms and they held long enough to get back to the City Campground [BTW, I don't know if I mentioned it or not, but I loved the City Campground!]. The tire was flat within a few minutes of getting there, and I ended up being towed to the Honda dealer in Rapid City and bought a tire. We didn't get there until just a few minutes before closing, so I rode back to Spearfish with the tow truck driver. Somebody (sorry, guys, but I can't remember who) gave me ride back to Rapid City the next morning and I had to hang around and wait for several hours.
I have plugged tires for two of my Concours buddies and those plugs lasted. The Stop'n'Plug (is that there name?) guy at the IMSA motorcycle show in Denver this year told me that our problem was that we didn't pull the plugs back against the mushroom as we put air into the tire. He said not to cut the part that's left sticking out until you've got the tire inflate.