Hour three is the lead up to the bubble. Typically, as I pointed out in another post, the bubble breaks early in hour4. Hour three is getting there.

If you've made it to hour three, you're probably +points. So relax.

Wait,  you're going to start the hour 300 / 600 with 60 ante, and end 1000 / 2000  with 200 antes, odds are you have < 12000 chips so you can't afford to relax. Neither can anyone else. Not even the chip leader who may have 12-16000, typically not much more than 20000. Everyone around you is going to be hunting for chips. 

The math is simple, it takes 17.000 in chips to play Hour 3. If you don't have 17.000 in chips, you have to get them. Unfortunately for you, everyone has this problem. 

My advice: Don't go card dead. I've been there. Card dead in hour 3. Card dead in hour three no matter where you start from (and I started at the top of the leaderboard) is a brutal experience. The blinds and antes are relentlessly relieving your stack of chips. Everywhere around you non-card dead people are shoving 1/4 - 1/2 your stack and you can't call them. Event though you're the big stack, once you get to hour 3 you're not big stack enough to call much with any 2. On the other hand, I once saw a BB fold a 1.3BB bet. Don't do stupid stuff.