Pitches per season/year dispute

I keep hearing that kids who are 16 to 19 years old should only be throwing 1000 pitches per season and 3000 pitches per year with them having 4 full months off from throwing.

How many pitches per season/year should a 16 to 19 year old be throwing?

In my opinion, those quotations are broad-brush catchalls that tend to treat this populations in a bundle.

Pitchers are an individual that must be trained, coached, managed on a one-on-one basis.

On the other hand I can understand the application of such, even some of reasoning. In other words I can understand “some” limits due to the limited number of pitching coaches skilled enough to train, coach and manage the amateur ranks.

However to be honest about the numbers given - specifically, I can’t argue against or support them one way or the other. I just don’t know enough about the youth game.