Although Vastu gives more importance to direction yet shape of building is significant for every type of building, in other words we can say that both shape & direction are primary for the property. There is no other thought which is more important in Vastu shape or direction because if direction is incorrect then even good shape of property can't help and vice versa.
Gaumukhi generally is narrow from the entrance if North and East are suitable directions and goes broad from inside. Shermukhi is just juxtaposed to Gaumukhi having an extended North or East and narrow South or West which is considered inauspicious for residential purpose but suitable for commercial. Gaumukhi on the contrary have an extended South and West which is not auspicious for residential property.
We shall say that no property can be perfect in all terms and shapes but we need to consider the shape of property wisely before purchasing. To enjoy benefits of such shapes it is ideal to construct entrance as South or West while in regular shape properties only East or North entrance is preferred.