PA has had the system in place for many years. When my sons were going through parochial school( Catholic grads in 2009 and 2013), their 5th/6th grade teams would play PA, which sometimes had two teams in the same league. The PA guys were running the same thing that the
PA high school team ran.
The system did not give PA any real advantage over the other 5th/6th grade teams, but it sure gave their kids a leg up on learning the offensive system-four years worth of experience before the kids got to high school. It’s easier to be efficient on offense when the players have all the base plays and reads pounded into their heads with four years of practice and games. It’s also easier to figure out which kids can be effective QBs.