[PvK]

Seems to me that space stations can store and send troops to planets under ground attack, during the strategic orders (not during combat, unless you also have a transport to ferry them to the ground, and are using tactical combat).

It only works for the defender though since they officially own the planet.

As for time needed to take over a planet - many Earth wars have taken years to resolve, involving only a country or at most a continent. High-tech weapons might or might not speed this up, depending on the specifics, and how much destruction the attacker was willing to create.

Ideally (for realism/detail/interesting-situation nuts like myself) multiple nations could have ground forces coexisting on a planet and fighting it out, with control of parts of each planet, and forces able to remain even if one side controls all of a planet. Guerrillas, underground resistance, etc.

PvK