That's much wider than I understand it. I would only move the mic from 1 to 2 feet at a time, making a much smaller sample area. When I first tried it I was moving the mic much too far and getting unpleasant results. But if it works for you, who's to complain. I think I would try it again and move the mic about half as far next time.

I don't know if it matters (probably not), but the charts I've seen put the first 3 measurements in the row at the seating position, then the next 3 about 1-2 feet closer to the mains. Definitely don't put the mic outside of the mains.