There has been a lot of talk throughout this last year about the effects of high volume box jumps on the Achilles, and the safety steps you can use to prevent a rupture. Although many people have transitioned to stepping down from the box, which will definitely prevent a tear, i still feel that rebounding back up is a more efficient, and more beneficial for performance because of its training and use of the stretch reflex in the lower leg, which is also used in things such as running and double unders. However, its important to remember that the body takes time to adapt itself to the demands placed on it so don't just jump into high volume box jumping, gradually work into it and give yourself time to become prepared for greater volume. Here is a great K-Starr video discussing what can be done to keep things healthy, and movement patterns that predispose us to injury.