There are a lot of mountains in the US where you're going to spend hours driving up steep inclines. I used to live on the wrong end of a 2 hour uphill drive with one gas station in the middle. That road was steep enough that even a gasoline car couldn't make the trip without a full tank of gas.
I drive through mountains all the time, and have to fill up my car all the time. GP didn't say anything about multiple stops; what I inferred (because it's literally what he said) was that you can have unequal ascending and descending on a round trip - which is geometrically impossible! And even if we are talking about having to stop and get gas, you still get the same benefit of regenerative braking when you are descending, whether it be the first half or the second half of the trip.
Your comment makes you sound like a city boy.