rojo, I have to be blunt, JKs numbers are nonsense. He will tell you that he worked out the physics of the matter. He didn't. He pulled the numbers outa his a$$ and you, like a sucker, believed him.
I said this 15 years ago and in all those 15 years he has never even bothered to check his numbers against actual data. Never. Not once in all those years. He's deluded and you are deluded for believing him without even checking yourself.
Here's a reliable formula based on actual observations of what happens in an actual race:
For every meter of ascent in a distance race (this doesn't apply to hill sprints) you lose around 1 second and for ever meter of descent you gain back 1/3 of a second. Or around 3 seconds per 10 feet up and 1 secod per 10 feet down. Easy to remember and reliable. There are lots of silly formulae which underestimate how much time we lose uphill and gain downhill. Daniels' uphill calculation is reasonable accurate, but he overestimates the downill advantage.