It's a shocking statistic about how many academy players drop out of football entirely. I think I once heard an academy director saying that if 1 in 10 players made a first team appearance and 3 in 10 had a career in football then you were doing exceptionally well. I think Saints have just about done that over the last 10 years.
But bear in mind the huge number of kids that pass through an academy, there will be well over 100 at Saints right now from 10 years olds up to the development squad. Plenty drop out as they get older and more get brought in from other academies or satellite sites etc. So getting 10 of them to play for the first team would be pretty amazing, and 30 in the top four divisions is even less likely.
Unrelated: I saw Ben Reeves yesterday. That is all.