There are many occasions when using directed damage is the best option. These could be:
      1. Targeting PDUs on a capital planet (when you will face more fighters than you can possibly kill).
      2. The enemy has few of a key unit, such as command ships or scouts.
      3. When there is a strategic target like a tug deploying a MB, or even upgrading a battle station if the conditions are right.
      4. It is also appropriate when doing regular damage will only kill fighters or when only one round of combat will be fought.
      However, "letting it fall" should not be lightly dismissed. There are other primary motivators on how to allocate your damage. At certain times, using Directed Damage is not the right choice and letting it fall is:
      1. Blunting an offensive: If the enemy is attacking in large numbers, letting it fall (especially if he sticks around for numerous rounds of combat, like over a capital) may create so many cripples that he cannot field battle lines able to generate high enough combat potential to make it worth continuing. If you direct damage on a key unit, your opponent has only one hole to fill on the line, but three to four cripples pulled back means he must bring up his reserves faster. He will also have to start thinking about how get them out of the hex and repaired and if his forces are strong enough to defend against your counter attacks.
      2. Overwhelming repair facilities: True, a dead ship is gone for good (except for salvage), but crippled ships are gone for a time as well. If you have 10 ships at a repair facility that can only repair three a turn, you have taken those other ships out of the fight for two to three turns and made him spend Economic Points on repairs instead of new construction of probably more capable ships. Add a strike or two on FRDs or if your enemy is on an extended logistics line and it takes even longer to get them back, repaired, and back into the fight.
      3. Pursuit: Yes, you should try to pop a key unit if it is under your guns on pursuit, but do not blindly believe you always have to use Directed Damage against pursued ships. By letting it fall, your enemy may have to kill more hulls than you could have destroyed with Directed Damage (and for no salvage), or cripple healthy ships to protect the retreating cripples. If you are being pursued, you may have the firepower to use Directed Damage on one of your pursuers, but letting it fall may leave three to four cripples he will have to use expensive field repair for or leave crippled for your turn.
      4. When they are all the same: If you are facing nothing but "vanilla" ships (i.e., no variants or rare hull types), go for volume. Make lots of cripples and let him deal with the cost and logistics of dealing with them.
      5. To drive your enemy nuts: If you always use Directed Damage, he will start basing some tactical decisions on that. If he thinks you will only kill one key unit, he may load up his battle line to get a really high combat potential, confident only one will die. Just throw him a curve and let it fall. Now he may have to cripple three or four hulls and deal with getting them out (pursuit) and fixed (repair).
      Directed Damage has and will always have its place, but sometimes it is better to just let it fall.