Once the gymnast has a fair snap down from folding mats, they can begin practicing back handsprings with a spot. This is a good introduction to connecting a handspring from the hands-to-feet flying phase and is very helpful as initial preparation for roundoff back handsprings.
The snap down back handspring is a very helpful progressive step toward the round off back handspring. Advanced gymnasts may practice this combination to refine some back tumbling technical details such as turning over from hands to feet on a hollow single body unit and rebounding with a tight arch first flying phase while the shoulder area is open.
Piking down with knees bent and no arm repulsion at all is a very common novice mistake. There is not a flying phase and the feet touch the floor with the hands still down.
Here are several snap down examples some better than others. Back handsprings have two flying phases one from feet to hands and the second turning from hands to feet. Snap downs help gymnast to understand the second flying phase.
Snap down drills are closely related to the hands-to-feet motion on back handsprings required to add power and turn over to the rebound connecting a handspring to another handspring or to a somersault. The goal is to open the shoulder area and then pushing from shoulders and wrists snap the whole body into a deep hollow while turning on one unit from hands to feet.