Dragon Ball Z Kai doesn't do as good a Job with the Buu arc as it does with the others. At least in terms of shortening the episode count. 

The first three major arcs (I'm counting Saiyan, Frieza and Cell) span 194 episodes in the original cut. In the Dragon Ball Kai cut, its 98 episodes. 

Majin Buu's arc, including the tournament, the Great Saiyaman and Gohan's school stuff and End of Z, runs 97 episodes in the original cut.

But rather than cutting it in half, its cut to seven tenths. 69 episodes. 

If any arc needed to be cut in half, it was the Buu arc, which drags on and on and on. I would have enjoyed Buu more if it ended about 20 episodes sooner. It stands out after the rest of DBZ Kai proceeds at such a brisk pace.