Yes? And use them as feeders for their core worlds. It’s always a mad dash for colonies the only problem is in 3 your could make an exploration period by making a large map with a low AI count. 4 seems continue the exploration phase later into the game with the subspace streams but the early game is just crazy intense.

All of these small colonies that you end up with when you when a war(s) is won and you destroy an AI Race(s) will end up eating a LOT of Food, i.e. you are likely to have bad starvation problems sooner or later if you are pursuing a military conquest approach/victory.