I have booted tires few times then been able to limp home. Never had a serious enough mechanical to stop my ride other than one tire incident. As far as breaking a spoke, if you knwo how, you can work with surrounding spokes to get the wheel fairly near true. I've done it for friends but I myself haven't broken a spoke in 8 years or so since I started building my own.
One time I was up in the mountains when my rear tire bulged like a bull frog on the climb. I tried to baby it back across a flat section then it blew straight center tread. Found out later that the tire company had some QC issues. I used their tires for years no problem till this and a second tire also had issues. Needless to say I don't use them anymore.
The time my tire failed, I had to wait 3 hours for my support vehicle.
No way was I descending a 12% grade at 40 mph, or even 5 mph with a severely damaged and booted tire.
