Training & O/B

This morning, our assignment was out & backs. I know I've explained these before, but now that I've experience several times, including twice this week, I'd like to expand.
First - let me remind you what they are -
Out & Backs - "the objective is to control your pace on the way out and then return 2-5"/minute faster on the way back. i.e. if you ran out for 2', then your return trip shouldn't be faster than 1:50. If so, then run out harder on the next set. The recovery is 60". "




Our first week, the time frame was 2 minutes, second week was 3 minutes, today was 4 minutes. 
Here is a picture of me doing 2 minute out & backs
Wiki
Here is a picture of me doing 3 minute out & backs
source, I'm on the left

Me doing 4 minute out & backs
source
The thing is, I can do anything for 2 minutes. I can keep up with the best of them for 2 minutes. Surprisingly, I did okay on the 2 minute out & backs, even though they were 4 minutes total because I did a pretty good job of pushing myself/pacing myself to come back quickly. 
Fast forward to an 8 full minutes of essentially running at a faster pace, I struggled. In addition to the challenge of that, I had to figure out how to adjust my pace to go up hill. Our out was up hill, and our back was downhill. The difference between your out and back can't be more than 5-10 seconds per minute out so it's not like I could just chill going out and kill it on the hill coming back. No - I had to actually push hard up the hill, but not too hard that I pooped out before the top of the hill and not too hard that I couldn't punch it coming back so that I would beat the 4 minutes. AAAGUUUUGHHUAHGUAHKLHAUHRJEDFUAHG
But I will say that if this doesn't make me faster, nothing will! 
Have you ever done out & backs? Do you like tempo/speed work?