I guess we should leave those decisions up to the people who are there to make them. My point is that one night of putting your feet up does not hurt in the greater scheme of things. You might actually feel you need it or even deserve it and to put a blanket "You must study every single spare minute of your time" is actually counter productive. Think about it, in all your life experiences... School for example, did you spend friday nights studying or relaxing? Uni, same question. OTS/ADFA, same question. BFTS/2FTS, same question. etc etc. You have two days in Saturday and Sunday in which you can study for 16hrs if you please, what's 6 hours of one night?
How much study can one candidate do whilst on Flight Screening? Once you know everything, you know everything... Once you're prepped for the OSB, you're prepped for the OSB... Apart from chair flying there isn't much else you can do.
That is my opinion and have seen it work. I've also seen it fail, but then again i've also seen the other argument work/fail.
I think we should leave it up to the individual.