With solid mechanics, I like step-backs. Start short with whips then work your way back until walk-through's are needed.
Maybe something like this:
-Starting at 3/4 distance, hit the glove (or zone) 2 out of 3 times to earn a step back.
-If you fail to earn a step back after two tries, you start over.
Keep track of the distance earned for the next try, or future sessions. No more than two attempts in a session before moving up to regular distance for spots and spins.