Each tier 9 planet was far away from the others. There were a few reasons for this but primarily it was because for a tier 9 planet to exist, a correspondingly big star must be attached to it. There could not be two stars of such sizes near each other as usually to form such a big star it uses its strong gravity to pull in all matter and energy around it. Simply put there was no one place in the universe that was filled with energy enough to birth two tier 9 planets. As such, the travel time between each tier 9 travel was at least a few months with even the fastest ships or travel artefacts. This was one of the biggest reasons why all-out war between two of the tier 9 planets was not seen often as it required a grudge strong enough to transfer billions of troops for at least a month of travel and that was just with the ships made by the Dwarfs or the Lazarus.