Just my two cents;
The kids you guys are talking about are 10 years old, correct?
Worrying about strength and conditioning programs for 10 year olds seems to be overkill. These kids need to be just that, KIDS.
At 10 they need to be shielded from overthrowing and overuse. I know we all want what’s best for our kids, but a 10 year old needing a pitcher’s conditioning program is, in my opinion, ridiculous.
I understand preventing injury and staying in shape. How about letting them be kids? Run around, climb trees, play on jungle gyms. They will stay flexible and in shape. Want to prevent injuries? Limit the number of pitches they throw. Limit the number of times they take the mound.
At 10 they need to learn how to pitch. They need to learn solid basics to their mechanics. I guarantee their mechanics will modify and change as they grow and get stronger, so if they learn solid basic mehanics at this younger age it will be easier to maintain their mechanics and modify anything as needed when they hit their growth spurts.
I know right now some are studs and throw really hard for 10, but things change. Some burn out, some don’t progress to the college level. Heck, some don’t progress to the HS level.
My own son was one of those kids that at 10 was not very athletic and didn’t throw particularly hard. He wasn’t selected for the elite teams. What he did do was work on his mechanics with his pitching coach and played on lesser AA teams. Bottom line is he worked hard but still played like a kid. Funny thing happened when he hit 13, 14. He started “growing into his body”. He got naturally stronger, and bigger. he is only 15 now but he’s 6’1" , 180 lbs. Now he is lifting and conditioning for HS ball, but it is his solid mechanics that allow him to throw his fastball at 82-84.
Basics first then conditioning.