What about on road repairs of tubulars?

Rip 'em off, stick 'em on. You're not likely to be able to "repair" a tubular on the road (or, for that matter, in the comfort of your home). So you just pull the old one off, fold it up, and put the new one on. This all takes some prep work: the spare tire is usually one that you've riden on before so that it's been properly stretched; and both the rim and the tire have to have been pre-glued (with a tire contact cement) so the tire will stick once mounted. Also, it can be difficult to get the old tire off, if it's really glued tight. Finally, once the replacement tire is mounted, it takes a little fiddling around to get it centered (side to side) all the way around the rim. Experienced tubular changers can usually do this operation faster than replacing a tube on a clincher.
(answer courtesy of Dave Jordan)