The only heat generation/glue problems I ever had with tubulars was on a 155 mile ride in Florida with air temperatures near 100 F. Who knows what the road surface temperatures were that day. The issue that caused flats was not the glue between the tubular and the rim, but the glue between the base tape and the casing. Eventually it got soft enough to cause some slipping, but the base tape/rim glue job held just fine. Eventually enough rubbing between the base tape and the casing caused a stitch to pop so that the tube herniated and eventually punctured from rubbing between the base tape and the casing. I got two flats that day via that failure mode. Of course the failure mode was very benign in terms of bike stability as all it really did was create a very slow leak, the kind you can get from a "bruise" on the tube. OF course I am really careful in my tubular gluing. Many times when rolling off an old tubular the base tape stays on the rim and the casing rolls off. No big deal, but it does inspire a lot of confidence when cornering hard.