isn't that the goal of all defenses, winning time so you can destroy your opponent before it destroy you?
Lafiel The full shield strength will always apply the same anywhere for focus fire as long as it's the same shield.
in the case there is only one shield and assuming no shot where gonna miss and that all the part protected by the shield are equally valuable, the shield coverage doesn't matter if the shield catch all the shots, and if the shield doesn't catch all the shots, it means some shots are damaging your ship, which is not good if the parts are destroyed
in the case there are several shields, it's better to have each area protected by several shields instead of having only one shield assigned to each area, because you don't want your ship to take damage as soon as one shield is down