A Class masts are more fragile than say a Tornado mat but, they are still pretty strong.
Breaking an A Class mast normally has to do with the violence of a flip or pitch pole. The wind has to be too high or you have to do something to make the capsize extra violent.
Where you can get in trouble, is conditions you should not be out in in the first place. For example, turning downwind in 25+ and pitch poling(New Orleans a few years ago), you will likely break a mast. With 15-20 kt wind, you would have to do something stupid in addition to break a mast. Like jumping forward to to grab something. I have flipped and pitch poled many times in 10-12 by doing something extra stupid, with no breakage.
