[jiggawatts]

Consider a colony of bacteria multiplying by splitting. Each new pair of cells is independent and do not cooperate. Some die, some stay put. Nonetheless, the “colony” spreads and explores new territory with zero coordination of these activities. Certainly not an intelligent centralised leadership!

Even if our first interstellar colonies diverge immediately and some even turn into reclusive hermits, some may expand, repeating the cycle.

[throwuwu]

Hard to say what would happen but I think we still need to avoid the assumption that each star system remains relatively static especially over very long periods of time. You also need to consider the purpose behind colonization, if it is to spread the existence of your civilization to new worlds then no one says those worlds must be uninhabited.