It does work.
I have done it once on my mountain bike when I was stuck without a correctly sized spare tube, I always try to carry spares for my bike and my kids bikes but accidentally grabbed 2 24 inch instead of a 26. I cut the tube at the hole by running it over my chainring a few times then tied it together, pumped it up a bit and stuffed it into the tire then pumped it up to about 45 - 50 lbs. It felt a little lumpy but got me home. This was with a 2.35 inch wide tire and wide rims, I suspect this would be much more difficult with a narrower tire/rim combo.
One of the guys I work with mountain bikes a lot and told me about a guy in their riding group that got a big gash in his sidewall when they were a long way from any help and they were unable to make a tire boot that would contain the tube. Apparently they stuffed the tire full of leaves and twigs and he was able to limp along.