[lawn]

I'll suggest that a 3-3 invasion is still a bad move for amateurs because they don't follow it up correctly and it may hamper their learning.

[Wildgoose]

Agreed. With a 3-3 you are trading away influence in favour of hard territory. AI is happy to do that very early because AI can effectively destroy influence. Human players need to learn to enter 3-3 at "the last possible moment". That requires judgement.