This is effectively what happens but not for that reason. Take the CIA and NSA, and then the FSB and GRU - within each you have different operational groups wit

This is effectively what happens but not for that reason. Take the CIA and NSA, and then the FSB and GRU - within each you have different operational groups with different practices and techniques each uniquely developed. Some are more advanced than others based on both the spread and importance of the target. Further, within these groups they would again separate out their techniques based on the importance of targets. Where this is an issue, which goes against your point - the groups can step on each other toes. The discovery of the broader and more detectable attacks invites attention, further scrutiny and additional forensics which may uncover the more sophisticated attacks. Where the real deceptive action takes place is in learning how other opposing groups operate and mimicking their tactics to make the process of attribution more difficult.