I do keep some overseers(5-10) in late game but I guess I go for more of a quick kill fleet.
In late game with all supply used I only use 2 armies with similar makeup.......2 kortuls 2 sikantras(which I use for healing and manual cast of bombers) 2 evacuators 1 marauder and 1 devastator... I put similar ships with different autocasts....except the sikantras.
I then have 10 scouts for mines,10 assailents, 15 sentinels, 15 carriers, 15 subverters,5 overseers and 20 enforcers.. I dont build the planet bombing ships since I am so cap ship heavy
I am a dumby though since I've been playing the game this long and didnt know the overseers heal ships.. I thought they just had that jump degredation crap. DOH!!!!!!!!!!!!!!!!!!!!!!
maybe i shouldnt be giving advice.. On the other hand I can beat the highest difficulty on large and huge maps.