I have used a turret beachhead to drain enemies of reinforcements and prevent build-ups on in-bounds I don't want to pay attention to. There was also a reverse scenario back when knowledge hacking was easy, where I turreted a core-world to bring in a Sci-Lab III.
If anyone wants to use beachheads, try playing against a Grav Driller AI. A cluster of quickly built Missile and Sniper Turrets works wonders against any in-supply planet with a Gravity Drill.
I'm relying on a small team of Spirecraft in my LP (on hold right now) - building a beachhead may actually be a good idea.
