Someone recently asked my opinion of the long toss drill. Like any tool or drill it can be as harmful as it is beneficial.
There is no magic bullet. If a kid has any one of a dozen imbalances, flexibility issues, or improper movement patterns in the shoulder, you may be trying to override dysfunction with power, a recipe for disaster.
We have a very specific protocol for long toss. Before going in that direction, we want to be sure the kid can benefit from it. Even then, the way they do it must fit within the whole program we design for her or it can exacerbate bad habits and add to existing strength imbalances.
Bottom line: Great concept. Like anything else, it can do more harm than good if someone just blindly grabs things off the shelf. It can be like trying to drive a tack with a sledge hammer. The peripheral damage can be frightening.