I never repaired tubes on the road. I always replaced the tube, and took the old one home with me to be repaired at my leisure.
This past Friday, I flatted outside a library with an outside sitting area. The sun was out, it was warm, and I had a comfortable place to sit, so I patched the tube. Not a bad experience at all.
I did use the Park glueless patches because I wanted to see if these do in fact suck. I did sand the area to be patched really well and so far so good. We'll see how it goes.