George -
Throat erosion is caused by heat. The faster a barrel is heated up the faster the potential for throat erosion occurs. If a barrel is subjected to firing 30 rounds in a minute it is going to get much hotter and not have time to dissipate the heta from fast firing/mad minute syndrome.
If the same barrel is fired with 30 rounds in 15 minutes time it will build up excess heat at a much slower rate, virtually nil. The potential for throat erosion is significantly reduced.
Protection from throat erosion is a function of fire discipline not barrel contour. Throat erosion will still occur when a barrel is fired at 1 round per minute but it is not accelerated as it will be when a barrel is fired at 30 rounds per minute.
Heavy profile barrels will heat up slower per unit time but they will also cool at much slower rate than a lighter profile barrel.
Charles.