Yeah, I dont think that's the problem. From my two formations, the first has shields preferred, the second has heavy armor and throwing weapons (hoping that'll get the palace guards placed there and not the legionaries, as they don't have throwing spears...) so the preferences don't overlap. I agree, the system needs an overhaul. Either specific spots beyond infantry/archers/cav or a way to put the units in a formation outside of combat. Like, rather than having two drop-down menus in the party menu, let us be able to make tabs for each formation and place the units manually that way.