I’ve worked for NCS now a number of times, and whilst yes it might happen occasionally, I’ve never seen it happen because the staff are very on top of it and it’s taken extremely seriously. It’s a huge issue from a safeguarding point of view, especially because you can take part in NCS when you’re 15 which is under the legal age of consent.
If you manage to actually do it, prepare to get found out. Whilst putting a load of 16/17 year olds in dorms together may not result in a “shagfest”, it results in lots of gossip, and rumours, and ultimately someone will grass you up, whether intentional or not.
Plus, the dorms aren’t mixed gender (obvs), and they’re often on separate sides of buildings to avoid people sneaking around. Staff are on night duty always for a number of reasons, and room checks, registers etc are done, again for a number of reasons. It’s a shame your mates have wasted their parents money, I’ve got a strong feeling they’re going to be disappointed. I don’t see why at the age of 16/17, if you were that desperate to have sex, why spend 4 weeks somewhere where you’re categorically told you can’t have sex, rather than spending your summer away from NCS, where you’re pretty much free to do what you want.