Having seen builds shared by various players... flux-neutral builds (or as close to flux-neutral as possible) remain popular. Omitting missiles to spend more OP on other things is not as common, but nowhere near unheard of.
Feels like that's also where you don't need all five groups nearly as much.
There are designs where I want it to do exactly that, but will pilot the ship because I want it to do that from a specific angle (and thus holding fire until the right moment is important). I've made alpha strike builds that I really wish I could just have on "hold fire" and "nuke everything" modes once I pilot them into position, since the extra click is pointless for such a build. Ditto on certain laser boats or other ships.
Most obnoxiously, carriers. I like piloting carriers like the mora, but especially early game when I can't afford the build I want, I usually wind up with weaponry I want to always fire. I still want to pilot the ship so it doesn't get to far away from the fleet and so it gets all my characters "piloted ship only" bonuses, but I really don't want to be forced to remember to spam fire that one turret or salamnader that I couldn't put on autofire.
Just to make sure you're aware: if you have 4 groups or less, you can select an empty group and all your other ones will autofire. For builds like you're talking about, this seems pretty much ideal.
That said, it occurred that there's a fairly easy workaround for this on my end, without adding new controls. Made it so that if you turn autofire on when a group is already selected, it will autofire. Re-selecting the group will enable the override. Basically, the most recent action - selecting the group to take manual control of, or turning autofire on - will take priority.