My own anecdata: I've had five flats in my life.
- First was in winter. My truck slid into a curb and ruined the tire. I had a spare, and I did make sure to check air pressure in the spare periodically. However, I never tried to actually remove the spare before that point. The entire mechanism was completely rusted shut. I had to call a tow truck to get me anyhow.
- Next two were very slow leaks caused by picking up a screw. Leaks were so slow that I was able to wait until I got back home to worry about it. At that point I just fixed them with plugs. I didn't even bother to get proper patches put on the inside of the tires. The plugs worked perfectly for the rest of the tires' lifetime.
- I hit a pothole with my Leaf and ripped a hole in the sidewall. I didn't have a spare, and couldn't plug it. I had to wait a few hours for a tow truck. I was planning on replacing all of the tires within a few months anyhow, so I just went ahead and did that a bit early. But I paid a bit of a price premium because of the timing.
- My son (on his learner's permit) hit road debris in our Tucson. Again, ripped a hole in the sidewall. The Tucson had a donut spare, so we were able to replace it rather quickly and continue on our way with minimal delay. I was able to take my time afterwards and look for a decent price on an identical replacement tire.