The Target Wedge (more traditionally known as the Gap Wedge) fills the 'gap' between the Pitching and Sand Wedges.
I believe Tom Kite was one of the first to carry 3 wedges. He dropped the 2I and strengthened the loft on the 3I. In Golf My Way JN favored going "down the shaft" to control less than normal distances with the wedges. There seems to be an education in Jeff's bag.