It totally depends on the circumstances.
When I do the go to work, go to sleep, go to work, go to sleep... routine it doesn't matter how much sleep I get, I don't feel completely rested when I get up. I usually get 7-8 hours and wake up without the alarm at 8AM, but it doesn't matter.
When I go hiking, I sleep on the ground, usually get about 8 hours of restless sleep (read 3 hours of actual sleep), get up at 4:30-5:00AM and feel the best I ever feel in the morning. I'm pretty sure it has to do with actually doing something physical during my day.
It's weird.