Playing my first game as humans. I'm not too far into it and have 9 good colonies. However, I have noticed my neighbor Yor is out of control. He is spamming colony ships everywhere. He literally just settled Mars! He has settled at least 3 marginal planets (like Mars) that are deep within my territory and within the ZOC of better planets I already settled. I'm sure all these will culture flip but it is a bad sign of AI and game mechanics that AI Yor thinks settling Mars is a good idea.
Also, I am about 95% sure AI is bee-lining to planets that can be settled without first scouting (AI should be unaware planet even exist). I have never seen a Yor scout ship but somehow he is sending colony ships directly to planets that are way behind my lines.
Put aside the bad decision and probably cheating, I really do not like the spam aspect of settling right now. I think every planet that can be settled has been settled prior to the time ion drives were discovered (large map, all players).