To add more life, I populate the places players will see most and the rest I just leave quite bear. I think its a balance between performance and looking good. I will liven up airfields and targets usually. Maybe the docks. A few barrage balloons. Trains can have a good livening effect as they travel far and are really visable.
But for things like an AAA battery in a wood, just plonk them down
No one will ever see them.