I do a similar quality check when tying a square knot (right over left, left over right but without the bows - probably the default knot for something you don't intend to ever untie and don't have a Scout's encyclopedic knowledge of more specialized knots) - since it doesn't have the bows, the quality check is that it should have a line of symmetry whereas if you repeat the same direction twice the finished knot is more of a spiral, having no line of symmetry.