Deano, not everyone is as fast nor do they burn them up as quickly as you do. I've found that heat cycling will definitely extend the tire's "competitive" life.
After 5 or 6 heat cycles, my tires are definitely not competitive with a brand new set, but there is plenty of rubber left up to about 25 heat cycles.
Lately for budgetary purposes I have been running Hoosiers with 12-15 heat cycles in competitive qualifying and race sessions. They work just fine and I see no cords, however, they are probably 1-1.5 seconds per lap slower than a brand new set.
I've also found that running the Hoosier at the recommended hot pressures for a Viper of 43-48 PSI significantly extends wear characteristics. I believe many Viper racers are still running at 36-38 PSI hot because they like the feel better, but tire wear goes up significantly. Hoosier insists that we should avoid the temptation to run hot pressures below those recommended because there will be little or no performance difference, but significant tire wear differences.