[Saxon]

Here is my guess, though I would love to see a more confident answer.

You can set the level at which your ships stop pounding one target and switch to the next. This could be of use if you want to soften up a planet for invasion and, now that I mention it, the answer to a lot of complaints about planets getting glassed before an invasion fleet can come in. Take out 30% and you will have wiped out the defences as well as a bit of population.

It would also be useful if you are using shield bypassing weapons. Knock out the guts of a ship, then move on to the next one. Your ships will not “waste” a turn destroying the Last bit of each ship but take the fight to the next still fighting ship. This way you would take the punch out of enemies faster, taking less damage yourself, or at least damaging a lot more enemy before going down. They then have to wait around doing repairs while your “avenger fleet” comes to get them.

Of course, I could be wrong and I can not test while sitting in the office.