If it's a really long game that lasts over 7 hours then it's definitely not easy to play concentrated all the time. And as the main stage comes after those 7+ hours of play, no matter what you have to be on top of your game then or at least be more concerned and focused than your opponents are. So I think my least concentrated game comes in the middle of the tournament, usually I build a big stack and then don't get involved in too many hands as you won't be able to win them all at this stage but easily can bust out. So from my perspective that's the most calm stage, where you can sort of distract yourself but have to come back, once your stack dropped or the late stage approaches. That's vital to do, but may not be that easy.