A feat of immense co-ordination.

[Vincent, Thunder God]

I doubt it has anything to do with amibidextrousity to do. It's not that you're bad at using one of the hands, it's that the brain has trouble concentrating on two different shapes at once.

Yes, that's what the teacher said, and I agree. Being ambidextrous probably helps, but it's largely the difficulty of concentrating on both shapes at once that makes it so difficult. The teacher said it was impossible, and if you try to do it quickly, it probably is.

Maybe the others are finding it possible by doing it slowly, like Odd Eye.