First, I may have the mechanics wrong. So, please confirm or correct.
As I recall, when defending against incoming ASM, the mechanic behind your FC targeting the incoming ASM is that you need one FC to target each wave of incoming ASM. Each wave of incoming ASM is essentially the number of ASM launchers assigned to a single FC. So, figure 20 ASM launchers, four FC, and the 20 incoming ASM are divided into four ASM waves, each of which needs to be targeted with a separate FC. You can then assign any number of AMM launchers to your FC and take out a percentage of the incoming ASM. In fact, you can assign multiple FC to target each incoming wave of ASM.
Assuming I get a confirmation rather than a correction.
When I attack, I could have a vessel with 50 ASM launchers and 25 FC so that each FC is assigned to a single ASM launcher. This then creates 25 waves of ASM where each wave of ASM has a size of two ASM. All 25 ASM waves would arrive on target at roughly the same time. The defender then needs 25 FC to target each of the 25 ASM waves. Would this be an effective way of overwhelming defenses?