Splitting PD

[Suicide Junkie]

PD missiles can be very useful and entertaining too.

With no autofire built in, your ships will have to use their multiplexing to pick and fire at incoming missiles / fighters / etc.
Although each missile individually has 100% chance to hit, there are still the problems of lead-time and overkill.
The former involves the fact that your missile must reach the enemy missile before the enemy missile reaches your hull
The latter involves organization between ships and among the weapons of each ship. You want to spread out your targets, so that you don't waste missiles against targets that have plenty of missiles inbound.

Overall, you get a healthy mix of offense and defense chance. When the defense outnumbers the offence by a large margin, there is still a chance to score some hits. Missiles fired from short range are liable to hit their targets before the PD can land their shots. The defenders will also be firing a lot of overkill, wasting supplies.

As the number of attackers increases, the missile targets spread out more, and you get less overkill. Defense efficiency improves, although they still will suffer more hits due to the larger volume of fire incoming.