It is designed to help basketball centers and forwards develop rhythm, timing for rebounding, and scoring in the paint.
[1] Virtually every great forward and center since Mikan has practiced this drill.
Kareem Abdul-Jabbar describes teaching it to children he coached in his book A Season on the Reservation.
Shaquille O'Neal, who admired Mikan so much that he offered to pay for his funeral expenses, learned the drill from his coach Dale Brown, when O'Neal played college basketball at LSU.
The drill is more or less a standard practice procedure for all basketball "big men".