Well, first of all you should use actual warships for SO builds. I was having a little fun here and giving others an opportunity to post say an Aurora build which might be more optimized. Second, as you can see, S-modding in Heavy Armor and Xyphos fighters are really, really strong. The Xyphos have burst PDs and hang near your ship, so they will take care of PD too, but in addition deal crippling EMP damage and the range is not limited by SO. Paired with SO this leads to the main strategy for the AI controlled ships: circle to the rear, let the Xyphos cripple the engines (and also often the cannons so return fire is reduced), kill. The other broken combo is SO + missiles (especially PCL). But SO is strong enough that a Tarsus can win the Onslaught under player control without either.
Even if building capitals that are not SO it is usually enough to give it a Xyphos and install 2 extra PD guns at most. This is mostly OP equal to installing lots of PD, gives you Ion Beams and makes your PD flux free and work even when overloaded. Not doing so is usually inferior imho.
A big tell for when a ship is not optimized or is built by a more inexperienced player is overspending on PD. A recent extreme example I saw is putting flak in the Conquest's medium ballistic slots, which is just... bad. Those are some of the best offensive slots in the game which could be used to pressure enemies at base 1000 range, and 2 burst PD on the enemy facing side +Xyphos to cover the rear is enough PD vs even a fighter heavy and Reaper spamming Remnant Ordo. If you do stuff like that you will only get a good response out of ships where spamming PD is okay due to a surplus of OP and slots, like Onslaught. I think it would be fine to install nothing but PD on that ship and it would still do fine. This is not the case for most ships where you must not waste OP or slots and should agonize over every PD gun about whether you need it or not, and if unsure should try it without and spending the OP on something to improve combat performance instead.
I'll add that of course you should agonize over guns as well and not install unnecessary ones. To use the Conquest example, if you put tac lasers in the small energies then that will just make your big guns worse by making your flux stats worse, while the tac lasers themselves do almost nothing by comparison to your big guns, so it is a waste of OP and you should spend it on vents or hullmods to improve your ship instead. It might seem like a bargain with the tac lasers because with 4 tacs vs 1 Mjolnir you get roughly 4/5th the base DPS for 45% of the flux cost at a longer range. But when you look at it closer you will find that this damage has 1/4th the hit strength vs armor and deals soft flux, so most dangerous opponents can just dissipate it with their shields up, and no EMP either. Adding tacs will help you kill weak opponents faster but make you weaker vs strong opponents and that is a bad way to build a loadout when you were winning against the weaker opponents anyway. Ditto Graviton in the front medium energy mount (Ion Beam otoh adds EMP arcs and should be fitted there), by the way. The Conquest does not have enough OP to install and support both the tacs and Mjolnirs without ending up short on OP needed for the good hullmods and flux stats. So just install the Mjolnir and not the tacs and spend the rest to support the Mjolnirs, and I will say I am certain that the ship works better this way because I've tried to make the tacs work, too.
