Mao was the first time.
For vash that cyclops bitch was his FIRST TIME.
For lelouch this is his second time experiencing a geass user, wait no, didnt he contact another one in season 1?
And then you have the emperor too.
It would be a costly mistake to assume there arent more geass users out there.
It may be me, but he seems to have become more reliant on his support structures(black knights/chink-koku) than his main forte which is supposed to be his intelect.