But when you fail to block in such a manner, knowing how to cover up the head is much better than just getting punched in the head with no protection whatsoever. Like I said, in CLF I have been taught that all blocks can be strikes and all strikes can be blocks. However, is someone gets inside and I can't use a strike as a block, say I don't have time or the distance is wrong, I am darn well going to try to get my arm protecting my head. Also, I am taught to use footwork to get the punch to miss along with protecting myself. The arm is protection in case the footwork is not sufficient. Again, the more complete the style is in everything, the more options are open for different circumstances.