I've always assumed that leaf span mean from the tip of one leaf to the tip of the opposite leaf. But I could be wrong. Vanda size can vary a great deal. Some can get huge and others are more compact, with a much narrower leaf span. Blooming size can vary also. Some of the ascocendas and vascostylis are frequent bloomers that can bloom on very small plants. Some of the bigger vandas need to get quite large before they start blooming.