Last December I was out on the Roger Albert Clark Rally in Newcastleton in my son's Fabia vRS. We got a puncture and fitted the spare, later that day whilst clearing the stage, we got a second puncture! We were still 5 miles from the main road and a further 5 miles from Newcastleton, the second puncture would not inflate at all there was a hole in the sidewall, so we had to refit the wheel that had been punctured in the morning, a borrowed foot pump got some air in the tyre & we were able to drive about Half a mile before having to stop and inflate the tyre again. After some considerable time we got to Newcastleton, we asked the garage to repair the puncture but were told we' d have to wait a while, so we removed the wheel, inflated it using the garage air line only to find the tyre had 2 punctures, one in the centre of the tread and one just on the edge, which would not get plugged. My Motorhome was parked nearby so we used it's emergency fix & go to insert the gunk & inflate the tyre. It worked, my sond drove back to Tyneside and ran round for three days before getting the tyre replaced!
So don't knock the fix & go kits, whilst they don't replace a spare wheel, they can get you home.