[PvK]

Really it depends on the alien species/society/military in question. Personally, I rarely play as the same type of nation twice, except I think I have played the EEEvil Oooze three times, but their answer is something like "whoever the nearest meanest Ooozoid is. Kill! Kill!"

In general, though, ya in SE4 the star fleet dominates. A lot of that is due to the limited nature of the other types of units, though. If troops were organized into armies with experience and supplies and generals and they had to actually do detailed protracted battle on planets and weren't dead meat to planetary bombardment, then they might be more like their own branch of service.

Static units that stay on a planet often seem like they could be under local command in a different organization. But generally, unless doing heavy roleplaying, they can be snapped up and deployed to another location by the fleet.

I do however like playing "captain's games", where I give control of practically everything to the ministers, except a single squadron which I control myself. In that case I tend to severely limit which forces I am allowed to commandeer.

PvK