It depends on who you are, and what you are trying.
Wookiees, they have self-regeneration. Shielded Air-Force, and the Berserkers are very versatile. Hence that they are very defensive. You don't need to keep re-enforcing, simply because their units are just so damn hard to kill.
Trade Federation, who's specialty is their mass of mechs and rapidity of building. Are designed solely for mass producing, so they need workers for the resources.
The power of accurate observation is often called "Cynisism" by those who do not possess it.