Please understand. I'm really not trying to start a conflict with any of these opinions. Without taking "risk" there is no great reward with respect to increasing velocity. With respect to throwing hard, there has to be intent & the willingness to put in the work. The debate arises around how to conduct these actions while minimizing the risk of injury.
In researching various training methods & how the body responds & reacts to various methods, a common theme has emerged in what I am coming across & here it is. Sometimes a focused & intense "less," is "more."
If you are training to be a sprinter, you are not best served by going out & doing 100 sprints daily. The body does not work to react to this kind of stimulus to give you the desired result. It actually breaks down.
If you are training to throw gas, you do not go out & max long toss for 15 minutes 5X a week or run down a mound & launch baseballs into a net X times per week while chucking weighted implements all winter long.
There is a needle to thread here & everyone & every pitcher is different. So, the caution is to try to discover how to best achieve the maximum potential of the player while offsetting risk of injury. Signing up for a 1 size fits all velo or long toss program aint it. This is my main point.