GBM,
the more you post and try and insult and demean others, including posters who are successfully playing the game at levels you are not coaching and your son is not playing, like JH, the bigger the hole you dig, in my experience and opinion.
Frankly,I think others in this thread are again trying to be polite in describing how they envision a bullpen.
Since you want to come out and attack JH, I will be more direct and blunt: I have never heard of a good HS or college coach or pitcher speak of doing a bullpen of the type you describe.
For most, bullpens are done to simulate game situations and stay game ready and/or get game ready.
Having a pitcher in a bullpen throw to(at) one spot with a fastball until he can do it and then move to another until he can do it, and then throw them down the middle, until he can do it, sounds like LL, not HS quality play and coaching.
I don't believe the pitchers above LL get multiple chances in game situations to locate pitches in the way you describe you coach in bullpens.
As it relates to your new "dialogue," I would come at this from the perspective of a hitter and the parent of a coach who really studies hitting.
A good coach with a reasonably good hitter, in a 3-0 count, and the bases loaded will often, very often, coach them to look for a certain pitch in a very small zone.
If it is not in that small zone, then they take.
Right down the middle with a fastball(can I assume you also coach to take something off to get a strike?) would be your coaching right to the strength of the hitter.
In my view, you just made a .300 hitter a .400 hitter and a .400 hitter into .500 hitter and in HS, a .500 hitter into a .600 hitter, with the chance to drive in multiple runs and break a game completely open.
Nice coaching.
Good HS and above pitchers who don't work in bullpens the way you coach them usually have some command and have an idea about what they want to do in these situations.
They can locate pitches without being coached that they throw it right down the heart of the plate into the strength of a hitter. They can also do it knowing that the zone often expands 3-0.
They can do it because they practice it over and over and over in bullpens the way Bum, bsbl247, BOF and others are describing.
The thing which is amazing to me, and to use your term, "UNBELIEVABLE" is that you continue to post like you know everything and show you are completely un-coachable in what you don't know or other baseball strategies which exist.
I think cabbagedad might have mentioned something like that last week.