Correct Ziggy, at a minimum over the last 10 years, following the strategy of some Waves dads who are very involved with Randwick, a large number of Waves boys have been playing both together at school and in the Randwick Juniors, every Sat/Sunday for many years, and clearly combinations have been formed that eventually culminate in our Opens teams. Some also play league but the minority.
I am confident this strategy occurs in other schools, and aside from natural talent, is certainly a major contributing factor to success.