If I was running a flying school, and I accepted block prepayments, I would
not put the money into escrow because the whole point of getting a block of cash up front is that I can use it in my business! To reduce my overdraft, probably. Then if I go bust, the punters lose it, but hey they got a 10% discount in return for taking the risk
One could argue that even if an escrow account was used, the punter is more likely to continue training because he cannot have the money back. But I still don't think many schools will use escrow. I have never heard of one.