After seeing success in making a variety of bowl and vase shapes with and without buttresses, I began to experiment with the number of pieces I could use to make a visually successful bowl.  I found the four-piece bowl to work pretty well.  The increase from a two-piece to four-piece shape also decreased the stress on the finished bowl and seemed to strengthen it both in drying and firing.

 

Four-part bowl

Views of four-part bowls

Two-part bowl