Thats funny, because I had all those same thoughts before posting. During my lotus's maiden voyage home I managed to be the second person running over a beer bottle in a parking lot. I immediately pulled over, picked all the (thankfully) small shards out of the A048's, and then as I was pulling the plastic walmart bags (packed with clothes) out for my hotel stay that evening, also noticed the fix a flat. That moment made me wonder about what everyone else is doing.
I've only had one "couldn't make it home" flat (knock on wood) and it was an incredibly frustrating experience. One of my tires was super low on air, and when it got up to freeway speeds it went KAAPOW! If you're wondering why I drove on an incredibly flat tire to begin with, thats where the frustrating part comes in. It was passenger side rear wheel and when I left work I didn't know it was flat. Next day I come in to work and a co-worker says "oh you got a flat? I noticed that tire looked awful low." Of course he didn't say anything to me all day or AS HE WAS OUTSIDE WATCHING ME LEAVE THE PARKING LOT. Wasn't his fault but still...
Anyway, I was able to put on a donut in that situation and drive home. Not possible in the lotus right now. And regarding how long those donuts are built or how long they last, I think they must be tough guys - I drove 70 mph everyday for 3 weeks on a ten year old donut until I could afford some new tires!