I see. It would seems to make sense that throwing certain distances gradually reduces the stress on the arm and how they build up to their full velocity while throwing. When my son does bullpen I always stress follow through when he is warming up to throw. Velocity increase comes from putting extra effort into throwing, so I guess I can see how LT would achieve that just as a good Bullpen could.
In the past my son has had coaches that would do their own version of long toss, but they never did it correctly. They would always start them out close and gradually move them further apart but never stress throwing harder as they moved further apart, the throws would remain at a constant velocity and the arcs would just get bigger and bigger. Once they were further apart the coaches would never bring them gradually back together stressing the importance of throwing harder as they did. From that experience, I never bought into LT, mostly because I never saw it have any benefit on my son. Perhaps I should try a true LT practice with my son this year and see.