I suppose it comes up naturally, emerging from a typical situation: exit previous corner slightly past the edge (for whatever reason such as unexpected surface)

I suppose it comes up naturally, emerging from a typical situation: exit previous corner slightly past the edge (for whatever reason such as unexpected surface) so counter for recover, but wait a corner is coming, so counter again to set up for the coming turn. If it turns out to be faster, the machine will have learned it serendipitously.