A rafter might split when heavier roof tiles are installed or if the rafter has inconsistent grain or excessive knots.
Hip roof rafter repair.
Finally the hip roof may well serve as a mansard at certain angles of inclination of course.
This video shows how to repair a split rafter.
Fixing a rafter requires basic carpentry skills and the ability to work in.
The successful distribution of loads due to the peculiarity of the location of the main diagonal angular and hip rafters ensures high resistance of the entire system to deformation under the action of external application of forces.
With the proper tools anyone can do this.