It can build or reinforce your inner mental strengths
I've talked to American marines. They rate this stuff for building resilience and mental toughness. Albeit a 24 hour session would be lowball for them. I guess everyone has their opinion.
I would agree a 24 hour one-off not going to turn them into the SAS but chucking in a session like this right at the end of preseason is a worthwhile tactic to reinforce the "us against the world" mentality. Still, proof of the pudding is in the eating.
No, they are not going to be SAS after one 24 hour session. And I agree with your point about the us vs them. And valeo's emphasis on team bonding.
But I'd just say don't under-estimate what getting through a very challenging 24hour session like this can do for players. Hanging on for 5 more minutes of extra time under fatigue starts to look like hilarious trivia compared to being very hungry, very fatigued, very mentally and physically tired and grumpy and constantly harassed by some army hardarse for 24hrs.
lols
but anyway, I hope it works.