Reflex training was arguably the training that Leo was best suited at, out of the entire training regiment that Ben had created for him.
He had great reflexes, he knew it from the system evaluation and it showed in training as for a good while after his training started, Ben could not flick a single stone onto him, much to the veterans surprise.
The training ground that Ben had created for Leo's reflex training was a maze of sharp, pointy nails protruding from the earth positioned with deliberate intent to limit his mobility, creating a treacherous landscape that demanded not just agility but acute spatial awareness.
Sometimes there was only enough area to land one feet amongst the bed of nails, sometimes he could put both, however, the area was always barely enough to correctly land a feet as even a slice mis-judgment could lead to Leo hurting himself.