I've been flying 4 pilot, over 14 hour legs for over 10 years now, both as F/O (MD-11, ATL-NRT) and as Capt, so I've had a lot of time to think about what the best way to rest is.
What I've observed is....it's different for everyone. There is no one size fits all solution.
Some guys sleep like a log through moderate turbulance, some guys can't sleep at all, even when it's smooth as glass. As far as the break schedules, it's what ever you find that works best for you, but then you have to negotiate with 3 other pilots as to what works best for them.
If it were up to me alone, based on my experience, I would fly the first 25% of the flight, then go to bed for the middle 50%, then come back up front and fly the last 25%, approach and landing....UNLESS that last 25% is over 4 hours, as it often is, from JNB-ATL. In that case, I'd rather get my rest closer to landing, and not be sitting up there going into a comatose state, just as we are starting the descent.
If it really bothers them, guys will bid off it, but look around and you'll see that it is the most senior F/O seat in the house, and all of those guys could be flying domestic Capt. and some of them already did, but left that lifestyle to...
Get some rest, while getting paid to do it!
It seems that flying 5 legs a day to a 9hr. layover with a 6am push sucks more than a 14 hour buffett with 6 hours sleeping, on the way to happy hour!