Being able to estimate the distance you have walked is a REALLY useful skill to have and I am constantly working on it. Often I do not take a watch so estimating time is another skill. I'm pretty good at it as long as I can see the sun. On overcast days, it's a struggle. Going back to the car should take less time because I am going downhill mostly. But every time it SEEMS to take longer! I think the anticipation that it should be easy skews my perception of time. Mostly the last few miles out to a trailhead is through boring country, so that boredom also makes time drag. I look at my watch (when I have it) and think OMG, I have only been hiking 15 minutes? I swear it "feels" like an hour!