In fact, the two points are connected. The primary purpose of the technique is to prevent damage from the last fire field, but the reason this happens is because of how the SSA works. The amulet has a slight delay before it is consumed, and by removing it at the right time, the damage is simply not applied. This, in turn, also prevents the SSA from breaking at that moment. So while the focus may prevent the damage, the net result is that the amulet remains intact.